Dioon purpusii is a cycad

Cycad

Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...

 tree endemic to a very small region in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 (Oaxaca

Oaxaca

Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...

, Puebla

Puebla

Puebla officially Estado Libre y Soberano de Puebla is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 217 municipalities and its capital city is Puebla....

).

Name

The epithet purpusii, chosen by Joseph Nelson Rose

Joseph Nelson Rose

Joseph Nelson Rose was an American botanist. He was born in Union County, Indiana. His father died serving during the Civil War when Joseph Rose was a young boy. He later graduated from high school in Liberty, Indiana....

, is an homage

Homage

Homage is a show or demonstration of respect or dedication to someone or something, sometimes by simple declaration but often by some more oblique reference, artistic or poetic....

 to one of Rose's contemporaries, colleague Carl Albert Purpus (1851—1941) (cf. Echeveria setosa

Echeveria setosa

Echeveria setosa, commonly known as the Mexican fire cracker or the firecracker plant, is a member of the Crassulaceae family. It blooms from early to late April with bright red and yellow flowers. It is native to Mexico and is common throughout Puebla. They grow to about 3-6in in...

Rose & Purpus).

Description

Dioon purpusii grows about 5 meters high or taller, with a dbh

Diameter at breast height

Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements....

 about 40 cm being typical.

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....

 of D. purpusii look like long (80 to 160 cm.) feathers sprouting from the top of the trunk

Trunk (botany)

In botany, trunk refers to the main wooden axis of a tree that supports the branches and is supported by and directly attached to the roots. The trunk is covered by the bark, which is an important diagnostic feature in tree identification, and which often differs markedly from the bottom of the...

 at odd angles. They are compound, and can be flat or keel

Keel

In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...

-shaped, and are a dark, lusterless gray-green. Each leaf is composed of a rachis

Rachis

Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...

 with between 150 and 260 narrow (about 7–12 cm. long, 8–10 mm. wide), inserted leaflet

Leaflet

A leaflet in botany is a part of a compound leaf. A leaflet may resemble an entire leaf, but it is not borne on a stem as a leaf is, but rather on a vein of the whole leaf. Compound leaves are common in many plant families...

s attached. The leaflets are arranged along the somewhat flattened rachis in matching symmetrical pairs without alteration. They do not grow perfectly perpendicular to their rachis, but point up and away from the petiole

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...

, all at approximately the same angle (this can be 120 degrees, 180 degrees, or any angle in between). The first five to twenty centimeters (depending on the overall length of the leaf) are fully formed leaflets, which are straightly lanceolate with flat, dentate margins; those growing towards and at the end of the rachis reduce to mere spines.

Seeing the difference between male and female

Plant sexuality

Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....

 cone

Strobilus

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but many botanists restrict the use of the term cone to the woody seed strobili of conifers...

s is not difficult with D. purpusii. The seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

 cones (female) are large (35–45 cm.; 15–20 cm. diam.), pale brown and ovoid and contain similarly shaped seeds (3–4 cm. x 2.5–3.5 cm.) with cream-colored or white sarcotesta

Sarcotesta

The sarcotesta is the outermost fleshy covering of Cycad seeds. Below this layer is usually the sclerotesta, the coating that makes direct contact with the cycad seed. In some species, however, there is an intermediate layer that is thought to be used in water retention and storage....

s. The green or palidly brown pollen

Pollen

Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...

 cones (male) are long (20–30 cm.), narrow (7 or 8 cm. diam.), and also ovoid.

Pests

Infestation

Infestation

Infestation refers to the state of being invaded or overrun by pests or parasites. It can also refer to the actual organisms living on or within a host.-Terminology:...

s of Aulacaspis yasumatsui, otherwise known as cycad aulacaspis scale, have been known to affect D. purpusii.

Conservation status

The International Union for Conservation of Nature and Natural Resources has assessed its status (2003) as "Vulnerable", with numbers trending downwards.