Warea carteri
Encyclopedia
Warea carteri, common names Carter's pinelandcress and Carter's mustard, is a fire-dependent
annual herb
occurring in xeric, shrub
-dominated habitats on the Lake Wales Ridge
of central Florida
.
s. The plants usually have many slender, ascending branches forming an open, rounded crown
. The leaves lack stipules and are arranged alternately on the stem. Lower leaves
are lost by the time the plant flowers. Leaf size and shape varies with age and position on the plant. At the time of flowering, leaf petioles
range from 0.8 to 3.9 mm with blades 1 to 3 cm long. Towards the tips of stems, the leaves are smaller and narrowly elliptical to almost linear
, while closer to the bases of stems and branches, the leaves are larger and oblanceolate or spatulate
. All leaves are rounded at the tip, their margins entire, and their bases attenuate to cuneate
. The lower leaves can also be undulate, margined or lobed
. The many inflorescences of W. carteri are dense, rounded racemes with many flowers (60 or more). The flowers are radially symmetric, with four white linearoblanceolate sepals, about 4.5 mm long, and curved toward the center of the flower at the tip. The four petal
s are white, about 6.0 mm long, with more than half their length in the form of a slender claw. The petal's blade is nearly round with irregular margins. The six spreading stamens are irregularly subequal in length and arise from a nectar-producing floral disc. The ovary is superior, cylindric, about 2.3 mm long, and raised on a slender stalk (gynophore
) about 2 mm long. The sessile stigma has two lobes. W. carteri is protandrous: the anthers begin to dehesce
within an hour or two after the flower has opened. The stigmas are receptive until 2 to 4 days afterwards, by which time the stamens on that flower have dropped. Warea carteris fruit
is a silique, long, slender pod divided lengthwise by a partition (septum
). The pod is flattened, cylindrical in cross-section and gently curved along its length, which is 4 to 6 cm long and 1.5 mm wide. The pod is borne on a gynophore, which is a stalk-bearing pistil 5 to 6 mm long, above a spreading pedicel
, which is around 8.5 mm long. The pod carries numerous oblong seeds, each 1.5 mm long Fruits split apart passively to shed the seeds.
flatwood
s and sandhill
s of the Lake Wales Ridge in Highlands
, Polk
, and Lake
counties, in South Florida Slash Pine
forests of the Miami area in Miami-Dade County
, and in coastal scrub in Brevard County
. It has been found in yellow sand scrub at Lake Wales Ridge State Forest
. The current known distribution of W. carteri includes Highlands, Polk, and Lake counties on the Lake Wales Ridge in central Florida. It may occur in Brevard County on Florida's Atlantic coast.
and The Nature Conservancy
's Tiger Creek Preserve. At Archbold Biological Station, W. carteri occurs in scrubby
flatwoods
and in sandhill
s dominated
by Turkey Oak and hickory
, and is often found in the ecotone
between these two vegetation types. Because sandhills occur on yellow sand
s, W. carteri is often found in or near yellow sands. Several populations of W. carteri at Archbold Biological Station are adjacent to roads, firelanes, or in areas with historic human disturbance. At Tiger Creek Preserve, W. carteri is found in degraded sandhill habitat where Turkey Oak is abundant, in scrubby flatwoods, and in xeric hammocks
. The collection of W. carteri made in Brevard County
was in coastal scrub. In Miami-Dade County
, W. carteri was found in South Florida Slash Pine
(Pinus elliotti var. densa) flatwoods. Here it may have occupied some of the same sites as Tiny Polygala (Polygala
smallii
) and Miami Palmetto (Sabal
miamiensis), both of which occur in areas with a sandy surface rather than bare oolite
.
is important in keeping fruit- and seed-set high, and individual fecundity
high. Pollinator
s appear to be the limiting factor in fruit and seed production. Because aboveground populations fluctuate wildly, autogamy helps ensure fecundity and may be a key life history trait. Germination
in W. carteri occurs in late winter through early spring (January–March). Flowering occurs in September and October. Fruiting occurs in October and November, and dispersal
follows in November and early December. Preliminary observations of insect activity on W. carteri indicate it is a generalist with respect to pollination. A great diversity of insects visit the flowers, including native solitary bees, bumblebees, syrphids (known as hoverflies or bee-flies), wasp
s, flies
, beetle
s, etc. Within-plant movements by insects appear to predominate over among-plant movements. Because of this, and in combination with the close proximity of male and female flowers in an inflorescence, self-pollination probably is a regular method of reproduction in this species. There are no obvious specialized forms of seed dispersal in W. carteri. The silique
s do not open explosively; rather, the external walls of the fruit peel away from the central septum as the fruit slowly dries, exposing the mature seeds inside. The seeds drop passively to the ground or they may be flung a bit further if the plant is brushed. Its not likely that seeds are moved by wind once they reach the ground. Collection or movement of seeds of W. carteri by ants or other animals has not been studied, but there are no obvious specialized structures on the seed that would encourage such movement. Large fluctuations observed in above ground population size suggest the possibility that seed banking plays a significant role in W. carteris biology. Environmental cues necessary for germination were explored experimentally at Archbold Biological Station. Moisture and light were found to be necessary for germination. The use of an oak leachate did not significantly affect germination. Some seeds stored in dry, dark conditions for 2 years germinated, demonstrating the potential of W. carteris seeds to remain dormant
at least that long. Firerelated cues such as heat do not stimulate germination, but germination does require light and seeds may remain dormant for more than 2 years.
var. gnaphalifolium (scrub buckwheat) and Prunus geniculata
(scrub plum) (K. DeLaney, Environmental Research Consultants, Inc., personal communication 1995). W. carteri does not seem to suffer badly from herbivory or predation by vertebrates or invertebrates, but a small percent of individuals do seem to suffer from the growth of a mold
or fungus
(M. Evans, Archbold Biological Station, personal communication 1995). There have not been any specific studies of W. carteris competitive relationships with other species. It is not clear whether the lack of above ground individuals in areas not recently burned is due to competition from other vegetation or if a direct effect of fire is necessary for germination (i.e. nutrient pulse, smoke, etc.). Although some persistent populations of W. carteri are found in openings in disturbed sites, populations in natural habitats following fire do not seem to be concentrated in openings between shrubs. In dense xeric hammocks though, they may prefer tree-canopy gaps.
scrub, scrubby flatwoods, and southern ridge sandhills) present before settlement was converted to other land uses by 1981. An additional 10.3 percent of the xeric vegetation was moderately altered, primarily by building roads to create residential subdivisions (Peroni and Abrahamson 1985). The situation is similar in Polk and Lake counties. Fire suppression has been in practice throughout W. carteris range
for many decades. Fire suppression is a threat to this species because its demography and reproduction seem to be closely tied to fire. The historical distribution of W. carteri includes the sites of at least 14 herbarium
collections made in what is now the Miami urban area in Miami-Dade County, from 1878 to 1934. Nearly all of the suitable habitat for the plant in this area has been altered by urban growth. The remaining tracts of native vegetation have been searched carefully in recent years.ec The plant is almost certainly extirpated from the county. Warea carteri has probably been extirpated from Brevard County as well as no specimens have been observed in recent years. The status of the two largest populations of W. carteri in central Florida (at Archbold Biological Station and Tiger Creek Preserve) has been monitored for 6 years (M. Evans, Archbold Biological Station, personal communication 1995). Extreme fluctuations of population size are observed year to year. The data accumulated on population sizes indicate a strong relationship with fire. W. carteri seems to respond quickly, strongly, and positively to fire. Major population increases and the discovery of new populations consistently occur 1 year after fire, while major population crashes, including the appearance of no above ground individuals, occur 2 years after fire. The demography of W. carteri is being studied at Archbold Biological Station, Tiger Creek Preserve, and the Lake Placid Scrub. Dozens of local patches are known from Archbold Biological Station and Tiger Creek Preserve, although not all patches have aboveground plants in any given year. At both Archbold Biological Station and Tiger Creek Preserve, many W. carteri populations have behaved fairly predictably in response to fire. Populations either appear or boom the year following fire (11 of 16 instances of population doubling at Tiger Creek Preserve occurred the year after a fire). Population crashes occur in the second year (18 of 26 populations at Tiger Creek Preserve lost more than 50 percent 2 years post fire). Populations in sites that have experienced prolonged fire suppression usually persist only in very low above ground densities. Warea carteri is currently protected at Archbold Biological Station, Lake Placid Scrub, Tiger Creek Preserve, Lake Wales Ridge SF, Snell Creek and Horse Creek. Polk County. BLM is in contact with the SFWMD and FWS to determine the best course of action to pursue in order to protect and manage W. carteri at this site.
(snakeroot), Polygonella myriophylla
(sand lace), Prunus geniculata
(scrub plum) and Conradina brevifolia
(short-leaved rosemary) (Johnson 1981), as well as Polygonella basiramia
(wireweed) and Dicerandra frutescens
(scrub mint) (Menges 1992). Warea carteri is a locally abundant annual that may remain dormant as seed for several years, so a population may have a substantial number of growing, flowering plants only in the first year after a fire. Because this species is conspicuous only when in flower, monitoring and finding populations is difficult. As previously mentioned, fire management is a critical concern for this species. Long intervals between fires are likely to result in the real loss of viable seeds from the seed bank
and declines in population sizes. The risk of extinction for this species is likely to be higher without proper fire management. For management considerations, it is important to realize that at sites where W. carteri is known to occur, individual plants or all the plants at a site may not appear above ground in any given year. One year of searching is not enough to know whether a given site has W. carteri. This species is inconspicuous except during a brief flowering period lasting about a month. In addition, its remaining habitat on the Lake Wales Ridge has not been thoroughly surveyed. As a result, the present distributional records are likely incomplete. The annual habit of Warea carteri, and its widely separated known localities, makes assessment of its status or planning its conservation more difficult than is the case for perennial herbs or shrubs.
Fire ecology
Fire ecology is concerned with the processes linking the natural incidence of fire in an ecosystem and the ecological effects of this fire. Many ecosystems, such as the North American prairie and chaparral ecosystems, and the South African savanna, have evolved with fire as a natural and necessary...
annual herb
Herb
Except in botanical usage, an herb is "any plant with leaves, seeds, or flowers used for flavoring, food, medicine, or perfume" or "a part of such a plant as used in cooking"...
occurring in xeric, shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
-dominated habitats on the Lake Wales Ridge
Lake Wales Ridge
The Lake Wales Ridge is a low ridge running for about 150 miles south to north in Central Florida. The greater part of the ridge is in Highlands County and Polk County, but it extends north into Osceola, Orange and Lake Counties. It is named for the city of Lake Wales, roughly at the mid point of...
of central Florida
Central Florida
Central Florida is a regional designation for the area surrounding Orlando in east central Florida, United States. The area represents the third largest population concentration in Florida, after the South Florida and Tampa Bay regions, respectively....
.
Description
Warea carteri is an annual herb, 0.2 to 1.5 m tall with erect green stemPlant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
s. The plants usually have many slender, ascending branches forming an open, rounded crown
Crown (botany)
The crown of a plant refers to the totality of the plant's aboveground parts, including stems, leaves, and reproductive structures. A plant canopy consists of one or more plant crowns growing in a given area....
. The leaves lack stipules and are arranged alternately on the stem. Lower leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
are lost by the time the plant flowers. Leaf size and shape varies with age and position on the plant. At the time of flowering, leaf petioles
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
range from 0.8 to 3.9 mm with blades 1 to 3 cm long. Towards the tips of stems, the leaves are smaller and narrowly elliptical to almost linear
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
, while closer to the bases of stems and branches, the leaves are larger and oblanceolate or spatulate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
. All leaves are rounded at the tip, their margins entire, and their bases attenuate to cuneate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
. The lower leaves can also be undulate, margined or lobed
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
. The many inflorescences of W. carteri are dense, rounded racemes with many flowers (60 or more). The flowers are radially symmetric, with four white linearoblanceolate sepals, about 4.5 mm long, and curved toward the center of the flower at the tip. The four petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are white, about 6.0 mm long, with more than half their length in the form of a slender claw. The petal's blade is nearly round with irregular margins. The six spreading stamens are irregularly subequal in length and arise from a nectar-producing floral disc. The ovary is superior, cylindric, about 2.3 mm long, and raised on a slender stalk (gynophore
Gynophore
A gynophore is the stalk of certain flowers which supports the gynoecium , elevating it above the branching points of other floral parts....
) about 2 mm long. The sessile stigma has two lobes. W. carteri is protandrous: the anthers begin to dehesce
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...
within an hour or two after the flower has opened. The stigmas are receptive until 2 to 4 days afterwards, by which time the stamens on that flower have dropped. Warea carteris fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a silique, long, slender pod divided lengthwise by a partition (septum
Septum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
). The pod is flattened, cylindrical in cross-section and gently curved along its length, which is 4 to 6 cm long and 1.5 mm wide. The pod is borne on a gynophore, which is a stalk-bearing pistil 5 to 6 mm long, above a spreading pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
, which is around 8.5 mm long. The pod carries numerous oblong seeds, each 1.5 mm long Fruits split apart passively to shed the seeds.
Taxonomy
Warea carteri was named by Small in 1909. A review of the genus by Channel and James in 1964 retained Small's treatment of the species. There are no scientific synonyms. Other common names for the species include Carter's warea, and Carter-warea.Distribution
From what is known of the historic distribution of W. carteri, it occurred in scrubbyFlorida scrub
Florida scrub is an endangered temperate coniferous forest ecoregion of the state of Florida in the United States. It is found on coastal and inland sand ridges and is characterized by a xeromorphic plant community dominated by shrubs and dwarf oaks. Scrub soils, a type of entisol, are derived...
flatwood
Flatwood
Flatwood is a soil series with impaired drainage that occurs in the southeastern United States. Flatwood soils are upland soils formed from marine sediments. A shallow water table plays a role in soil formation, typically the water table is only a few feet deep and fluctuates during the year...
s and sandhill
Sandhill
A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak dominated.Entisols are the typical...
s of the Lake Wales Ridge in Highlands
Highlands County, Florida
Highlands County is a county located in the U.S. state of Florida. The U.S. Census Bureau 2006 estimate for the population was 97,346. Its county seat is Sebring, Florida. The county comprises the Sebring, Florida, Micropolitan Statistical Area.- History :...
, Polk
Polk County, Florida
Polk County is located in central Florida between the Tampa Bay and Greater Orlando metropolitan areas. The county was established by the state government in 1861 on the eve of the American Civil War and named after former United States president James K. Polk. The county seat is Bartow and its...
, and Lake
Lake County, Florida
Lake County is a county located in the state of Florida, United States. As of the 2000 Census, the population was 210,528. The Census Bureau estimated the population in 2008 to be 307,243. Its county seat is Tavares...
counties, in South Florida Slash Pine
Slash Pine
Pinus elliottii, commonly known as the Slash Pine, is a pine native to the southeastern United States, from southern South Carolina west to southeastern Louisiana, and south to the Florida Keys....
forests of the Miami area in Miami-Dade County
Miami-Dade County, Florida
Miami-Dade County is a county located in the southeastern part of the state of Florida. As of 2010 U.S. Census, the county had a population of 2,496,435, making it the most populous county in Florida and the eighth-most populous county in the United States...
, and in coastal scrub in Brevard County
Brevard County, Florida
Brevard County is a county located in the U.S. state of Florida, along the coast of the Atlantic Ocean. As of 2007 U.S. Census Bureau estimates, the population is 536,521, making it the 10th most populous county in the state. Influenced by the presence of the John F. Kennedy Space Center, Brevard...
. It has been found in yellow sand scrub at Lake Wales Ridge State Forest
Lake Wales Ridge State Forest
The Lake Wales Ridge State Forest is in the U.S. state of Florida. The forest is located on the Lake Wales Ridge in Central Florida, near Frostproof.-References and external links:*...
. The current known distribution of W. carteri includes Highlands, Polk, and Lake counties on the Lake Wales Ridge in central Florida. It may occur in Brevard County on Florida's Atlantic coast.
Habitat
The two largest populations of W. carteri on the Lake Wales Ridge occur at Archbold Biological StationArchbold Biological Station
The Archbold Biological Station is a research institute with a surrounding estate near Lake Placid, Florida, USA. It includes an extensive area of Florida scrub, a scientifically interesting and highly threatened ecosystem...
and The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
's Tiger Creek Preserve. At Archbold Biological Station, W. carteri occurs in scrubby
Florida scrub
Florida scrub is an endangered temperate coniferous forest ecoregion of the state of Florida in the United States. It is found on coastal and inland sand ridges and is characterized by a xeromorphic plant community dominated by shrubs and dwarf oaks. Scrub soils, a type of entisol, are derived...
flatwoods
Flatwoods
Flatwoods, Pineywoods, Longleaf Pine-Wiregrass Ecosystem refers to an ecological community in the Southeastern coastal plain of North America...
and in sandhill
Sandhill
A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak dominated.Entisols are the typical...
s dominated
Oak-hickory forest
The oak-hickory forest is a general type of North American forest ecosystem with a range extending from southern New England and New York, west to Iowa, and south to Northern Georgia. Smaller, isolated Oak-Hickory communities can also be found as far west as North Dakota, south to Florida and...
by Turkey Oak and hickory
Hickory
Trees in the genus Carya are commonly known as hickory, derived from the Powhatan language of Virginia. The genus includes 17–19 species of deciduous trees with pinnately compound leaves and big nuts...
, and is often found in the ecotone
Ecotone
An ecotone is a transition area between two biomes but different patches of the landscape, such as forest and grassland. It may be narrow or wide, and it may be local or regional...
between these two vegetation types. Because sandhills occur on yellow sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
s, W. carteri is often found in or near yellow sands. Several populations of W. carteri at Archbold Biological Station are adjacent to roads, firelanes, or in areas with historic human disturbance. At Tiger Creek Preserve, W. carteri is found in degraded sandhill habitat where Turkey Oak is abundant, in scrubby flatwoods, and in xeric hammocks
Hammock (ecology)
Hammocks are dense stands of hardwood trees that grow on natural rises of only a few inches higher than surrounding marshland that is otherwise too wet to support them. Hammocks are distinctive in that they are formed gradually over thousands of years rising in a wet area through the deposits of...
. The collection of W. carteri made in Brevard County
Brevard County, Florida
Brevard County is a county located in the U.S. state of Florida, along the coast of the Atlantic Ocean. As of 2007 U.S. Census Bureau estimates, the population is 536,521, making it the 10th most populous county in the state. Influenced by the presence of the John F. Kennedy Space Center, Brevard...
was in coastal scrub. In Miami-Dade County
Miami-Dade County, Florida
Miami-Dade County is a county located in the southeastern part of the state of Florida. As of 2010 U.S. Census, the county had a population of 2,496,435, making it the most populous county in Florida and the eighth-most populous county in the United States...
, W. carteri was found in South Florida Slash Pine
Slash Pine
Pinus elliottii, commonly known as the Slash Pine, is a pine native to the southeastern United States, from southern South Carolina west to southeastern Louisiana, and south to the Florida Keys....
(Pinus elliotti var. densa) flatwoods. Here it may have occupied some of the same sites as Tiny Polygala (Polygala
Polygala
Polygala is a genus of about 500 species of flowering plants belonging to the family Polygalaceae, commonly known as milkwort or snakeroot...
smallii
Polygala smallii
Polygala smallii is a rare species of flowering plant in the milkwort family known by the common name tiny polygala, or tiny milkwort. It is endemic to Florida in the United States, where it is limited to the southeastern coast of the peninsula. The plant is now only known from eight sites, with...
) and Miami Palmetto (Sabal
Sabal
Sabal is a genus of New World palms, many of the species being known as palmetto. They are fan palms , with the leaves with a bare petiole terminating in a rounded fan of numerous leaflets; in some of the species, the leaflets are joined for up to half of their length...
miamiensis), both of which occur in areas with a sandy surface rather than bare oolite
Oolite
Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Hellenic word òoion for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites...
.
Reproduction
Experiments have demonstrated that Warea carteri is self-pollinating, autogamous, and self-compatible. Autogamy and selfcompatibility allow isolated or sparsely distributed individuals to reproduce. Natural levels of fruit- and seed-set are quite high, with a fruit-set of 62 percent, and seed-set of 50 percent. Self-pollinated flowers showed significantly lower fruit- and seed-set, 41 percent fruit-set and 28 percent seed-set. This indicates that insect-mediated pollinationPollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
is important in keeping fruit- and seed-set high, and individual fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
high. Pollinator
Pollinator
A pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...
s appear to be the limiting factor in fruit and seed production. Because aboveground populations fluctuate wildly, autogamy helps ensure fecundity and may be a key life history trait. Germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
in W. carteri occurs in late winter through early spring (January–March). Flowering occurs in September and October. Fruiting occurs in October and November, and dispersal
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
follows in November and early December. Preliminary observations of insect activity on W. carteri indicate it is a generalist with respect to pollination. A great diversity of insects visit the flowers, including native solitary bees, bumblebees, syrphids (known as hoverflies or bee-flies), wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s, flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, etc. Within-plant movements by insects appear to predominate over among-plant movements. Because of this, and in combination with the close proximity of male and female flowers in an inflorescence, self-pollination probably is a regular method of reproduction in this species. There are no obvious specialized forms of seed dispersal in W. carteri. The silique
Silique
A silique or siliqua is a fruit of 2 fused carpels with the length being more than three times the width. The outer walls of the ovary usually separate when ripe, leaving a persistent partition...
s do not open explosively; rather, the external walls of the fruit peel away from the central septum as the fruit slowly dries, exposing the mature seeds inside. The seeds drop passively to the ground or they may be flung a bit further if the plant is brushed. Its not likely that seeds are moved by wind once they reach the ground. Collection or movement of seeds of W. carteri by ants or other animals has not been studied, but there are no obvious specialized structures on the seed that would encourage such movement. Large fluctuations observed in above ground population size suggest the possibility that seed banking plays a significant role in W. carteris biology. Environmental cues necessary for germination were explored experimentally at Archbold Biological Station. Moisture and light were found to be necessary for germination. The use of an oak leachate did not significantly affect germination. Some seeds stored in dry, dark conditions for 2 years germinated, demonstrating the potential of W. carteris seeds to remain dormant
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
at least that long. Firerelated cues such as heat do not stimulate germination, but germination does require light and seeds may remain dormant for more than 2 years.
Relationship to Other Species
Warea carteri typically occurs in dry oak sites where other scrub endemics are scarce and at the ecotone between scrub and high pineland with other plants: Eriogonum longifoliumEriogonum longifolium
Eriogonum longifolium - Longleaf Eriogonum or long-leaf wild buckwheat - is a dicot of the family Polygonaceae. In addition to populations of E. longifolium var. longifolium found in Arkansas, Kansas, Louisiana, Missouri, New Mexico, Oklahoma, and Texas, there are varieties or subspecies that are...
var. gnaphalifolium (scrub buckwheat) and Prunus geniculata
Prunus geniculata
Prunus geniculata is a rare species of plum known by the common name scrub plum. It is endemic to Florida in the United States, where it occurs on the Lake Wales Ridge in the central ridges of the peninsula...
(scrub plum) (K. DeLaney, Environmental Research Consultants, Inc., personal communication 1995). W. carteri does not seem to suffer badly from herbivory or predation by vertebrates or invertebrates, but a small percent of individuals do seem to suffer from the growth of a mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
or fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
(M. Evans, Archbold Biological Station, personal communication 1995). There have not been any specific studies of W. carteris competitive relationships with other species. It is not clear whether the lack of above ground individuals in areas not recently burned is due to competition from other vegetation or if a direct effect of fire is necessary for germination (i.e. nutrient pulse, smoke, etc.). Although some persistent populations of W. carteri are found in openings in disturbed sites, populations in natural habitats following fire do not seem to be concentrated in openings between shrubs. In dense xeric hammocks though, they may prefer tree-canopy gaps.
Status and Trends
Warea carteri was listed as an endangered species in 1987 due to habitat loss (52 FR 2234). The primary threats to W. carteris persistence are habitat destruction and fire suppression. On the Lake Wales Ridge, W. carteri is threatened primarily by the conversion of its habitat to citrus groves or residential subdivisions. In Highlands County, 64.2 percent of the xeric vegetation (sand pineSand Pine
Pinus clausa is a small, often shrubby tree from , exceptionally to tall, found in two separate locations, one across central peninsular Florida, and the other in the western Florida panhandle and the Alabama coast; there is a range gap of about between the populations...
scrub, scrubby flatwoods, and southern ridge sandhills) present before settlement was converted to other land uses by 1981. An additional 10.3 percent of the xeric vegetation was moderately altered, primarily by building roads to create residential subdivisions (Peroni and Abrahamson 1985). The situation is similar in Polk and Lake counties. Fire suppression has been in practice throughout W. carteris range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
for many decades. Fire suppression is a threat to this species because its demography and reproduction seem to be closely tied to fire. The historical distribution of W. carteri includes the sites of at least 14 herbarium
Herbarium
In botany, a herbarium – sometimes known by the Anglicized term herbar – is a collection of preserved plant specimens. These specimens may be whole plants or plant parts: these will usually be in a dried form, mounted on a sheet, but depending upon the material may also be kept in...
collections made in what is now the Miami urban area in Miami-Dade County, from 1878 to 1934. Nearly all of the suitable habitat for the plant in this area has been altered by urban growth. The remaining tracts of native vegetation have been searched carefully in recent years.ec The plant is almost certainly extirpated from the county. Warea carteri has probably been extirpated from Brevard County as well as no specimens have been observed in recent years. The status of the two largest populations of W. carteri in central Florida (at Archbold Biological Station and Tiger Creek Preserve) has been monitored for 6 years (M. Evans, Archbold Biological Station, personal communication 1995). Extreme fluctuations of population size are observed year to year. The data accumulated on population sizes indicate a strong relationship with fire. W. carteri seems to respond quickly, strongly, and positively to fire. Major population increases and the discovery of new populations consistently occur 1 year after fire, while major population crashes, including the appearance of no above ground individuals, occur 2 years after fire. The demography of W. carteri is being studied at Archbold Biological Station, Tiger Creek Preserve, and the Lake Placid Scrub. Dozens of local patches are known from Archbold Biological Station and Tiger Creek Preserve, although not all patches have aboveground plants in any given year. At both Archbold Biological Station and Tiger Creek Preserve, many W. carteri populations have behaved fairly predictably in response to fire. Populations either appear or boom the year following fire (11 of 16 instances of population doubling at Tiger Creek Preserve occurred the year after a fire). Population crashes occur in the second year (18 of 26 populations at Tiger Creek Preserve lost more than 50 percent 2 years post fire). Populations in sites that have experienced prolonged fire suppression usually persist only in very low above ground densities. Warea carteri is currently protected at Archbold Biological Station, Lake Placid Scrub, Tiger Creek Preserve, Lake Wales Ridge SF, Snell Creek and Horse Creek. Polk County. BLM is in contact with the SFWMD and FWS to determine the best course of action to pursue in order to protect and manage W. carteri at this site.
Management
The natural fire return interval in the various vegetation communities W. carteri inhabits ranges from every 2 to 6 years for turkey oak-dominated sandhill, to every 6 to 10 years in scrubby flatwoods, to every 10 to 20 years in hickory-dominated sandhill (Myers 1990). Through demographic monitoring of W. carteri, it is becoming clear that fire is an essential management tool to maintain large populations of this species. As with other rare species, habitat protection is a key element to preservation of W. carteri. In the absence of fire, populations of W. carteri have survived in smaller numbers in areas of prior human disturbance, such as the margins of roads or firelanes. Several other Lake Wales Ridge endemics that are also federally listed appear to be favored by disturbance in this fashion including: Eryngium cuneifoliumEryngium cuneifolium
Eryngium cuneifolium is a rare species of flowering plant in the carrot family known by the common names wedgeleaf eryngo, wedge-leaved button-snakeroot, and simply snakeroot. It is endemic to the state of Florida in the United States where it is known only from Highlands County...
(snakeroot), Polygonella myriophylla
Polygonella myriophylla
Polygonella myriophylla is a rare species of flowering plant in the knotweed family known by the common names sandlace, woody wireweed, and Small's jointweed. It is endemic to Florida in the United States, where it is limited to the central ridges of the peninsula, including the Lake Wales Ridge....
(sand lace), Prunus geniculata
Prunus geniculata
Prunus geniculata is a rare species of plum known by the common name scrub plum. It is endemic to Florida in the United States, where it occurs on the Lake Wales Ridge in the central ridges of the peninsula...
(scrub plum) and Conradina brevifolia
Conradina brevifolia
Conradina brevifolia is a rare species of shrub in the mint family known by the common name short-leaved false rosemary. It is endemic to Central Florida, where it is known only from the Lake Wales Ridge. There are perhaps 36 occurrences of the plant remaining, and 10 of these are likely to be...
(short-leaved rosemary) (Johnson 1981), as well as Polygonella basiramia
Polygonella basiramia
Polygonella basiramia is a rare species of flowering plant in the knotweed family known by the common names wireweed, hairy wireweed, purple wireweed, and Florida jointweed. It is endemic to Florida in the United States, where it is limited to the central ridges of the peninsula, including the Lake...
(wireweed) and Dicerandra frutescens
Dicerandra frutescens
Dicerandra frutescens is a rare species of flowering plant in the mint family known by the common names scrub mint and scrub balm. It is endemic to Highlands County, Florida, where it is known only from the Lake Wales Ridge. Its habitat is quickly being lost as it is converted to residential and...
(scrub mint) (Menges 1992). Warea carteri is a locally abundant annual that may remain dormant as seed for several years, so a population may have a substantial number of growing, flowering plants only in the first year after a fire. Because this species is conspicuous only when in flower, monitoring and finding populations is difficult. As previously mentioned, fire management is a critical concern for this species. Long intervals between fires are likely to result in the real loss of viable seeds from the seed bank
Seedbank
A seedbank stores seeds as a source for planting in case seed reserves elsewhere are destroyed. It is a type of gene bank. The seeds stored may be food crops, or those of rare species to protect biodiversity. The reasons for storing seeds may be varied...
and declines in population sizes. The risk of extinction for this species is likely to be higher without proper fire management. For management considerations, it is important to realize that at sites where W. carteri is known to occur, individual plants or all the plants at a site may not appear above ground in any given year. One year of searching is not enough to know whether a given site has W. carteri. This species is inconspicuous except during a brief flowering period lasting about a month. In addition, its remaining habitat on the Lake Wales Ridge has not been thoroughly surveyed. As a result, the present distributional records are likely incomplete. The annual habit of Warea carteri, and its widely separated known localities, makes assessment of its status or planning its conservation more difficult than is the case for perennial herbs or shrubs.
External links
- Center for Plant Conservation National Collection of Imperilled Plants Profile: Warea carteri
- United States Department of Agriculture Natural Resources Conservation Service PLANTS Species Profile: Warea carteri
- United States Fish and Wildlife Service Species Profile: Carter's mustard (Warea carteri)