Luina
Encyclopedia
Luina, commonly called silverback, is a small genus
of perennial
shrub
s in the sunflower family (Asteraceae
).
The name of this genus is an anagram
of the flower genus Inula
.
, native to the western and the northwestern states of the USA, growing on rock outcrops, cliffs, and talus slopes.
Their slender stems
are covered with a gray, thick felt. They grow from a stout, branching, woody base, growing into clumps several meters across.
The leaves
have an alternate arrangement, The leaf shape is lanceolate to ovate. The leaf margins are entire or dentate. The leaves are sessile in L. hypoleuca, but petiolate in L. serpentina. The leaves are glabrous above, but underneath thick with white hairs, giving it a silvery appearance. Hence its common name : silverback.
At the end of each stem there is an inflorescence
with generally 4-12, flat-topped clustered flower
heads. These are discoid, i.e. they contain only disc flowers and lack the ray flowers. The bract
s under the flower head occur in 1-2 equal series. The receptacle is flat or convex.There are generally 11-23 bright yellow disc flowers, with a slightly expanded throat.
The glabrous or strigose fruit
is 3-4 mm long. The pappus shows many bristles and is 8-10 mm long.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
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...
s in the sunflower family (Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
).
The name of this genus is an anagram
Anagram
An anagram is a type of word play, the result of rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once; e.g., orchestra = carthorse, A decimal point = I'm a dot in place, Tom Marvolo Riddle = I am Lord Voldemort. Someone who...
of the flower genus Inula
Inula
Inula is a large genus of about 90 species of flowering plants in the family Asteraceae, native to Europe, Asia and Africa. The genus is thought by some to be paraphyletic, based on the study of the different phenolic compounds the various species have.They are mostly perennial herbs that vary...
.
Description
These are large, bushy perennialsPerennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
, native to the western and the northwestern states of the USA, growing on rock outcrops, cliffs, and talus slopes.
Their slender stems
Plant 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...
are covered with a gray, thick felt. They grow from a stout, branching, woody base, growing into clumps several meters across.
The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
have an alternate arrangement, The leaf shape is lanceolate to ovate. The leaf margins are entire or dentate. The leaves are sessile in L. hypoleuca, but petiolate in L. serpentina. The leaves are glabrous above, but underneath thick with white hairs, giving it a silvery appearance. Hence its common name : silverback.
At the end of each stem there is an inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
with generally 4-12, flat-topped clustered flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
heads. These are discoid, i.e. they contain only disc flowers and lack the ray flowers. The bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s under the flower head occur in 1-2 equal series. The receptacle is flat or convex.There are generally 11-23 bright yellow disc flowers, with a slightly expanded throat.
The glabrous or strigose 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 3-4 mm long. The pappus shows many bristles and is 8-10 mm long.
Species
- Luina hypoleucaLuina hypoleucaLuina hypoleuca is a species of the genus Luina and the family Asteraceae. Found in North America on open and usually rocky places between altitudes of 70–2100 meters in British Columbia, California, Oregon and Washington.-External links:***...
Benth. : Silverback Luina, Littleleaf Luina- Luina hypoleuca var. californica (A. Gray)
- Luina hypoleuca var. dentata L.F. Hend.
- Luina hypoleuca var. hypoleuca
- Luina serpentina Cronquist : Colonial Luina, Creeping Silverback