Roundleaf Oxytheca: Oxytheca Perfoliata

Roundleaf oxytheca is a species of flowering plant in the buckwheat family also known by the common name roundleaf puncturebract and the scientific name Oxytheca perfoliata. It is native to the southwestern United States, where it is a common plant of the deserts and some woodland and valley areas. It is a common plant in the Mojave Desert, with extensions along the Lahontan Trough into northwestern Nevada (to Humboldt and Washoe counties), and along the desert edge of California’s Transverse Ranges and the more arid portions of the San Joaquin Valley. It also occurs in the Sonoran Desert south to Imperial County.
It flowers from April to August and proliferates in rocky flats, washes, and slopes mainly in saltbush communities at elevations from roughly 1,900 feet to 6,000 feet inelevation in Arizona, California, Nevada and Utah.
The Oxytheca perfoliata is an annual herb producing a leafless stem up to slightly more than five inches in maximum height in the spring; during the winter the plant is a small rosette of oblong or spoon-shaped leaves a few centimeters wide. The plant is red-veined green, or often brown to maroon or magenta in color. The inflorescence atop the stem is punctuated by nodes at which the bracts are fused to form a cup or band up to about an inch entimeters wide. At the end of each branching of the stem is a similar cup of bracts partially fused around a cluster of flowers. The bracts are tipped in spinelike awns. The flowers are white to yellow-green and hairy in texture.
The stems are glandular distally and the leaf blades are spatulate to oblong or oblanceolate, with margins that are ciliate or otherwise gla-brous. Inflorescences open to densely branched bracts at first node,with triangular to lanceolate, 2-10 × 0.5-4(-8) mm, with awn 0.5-1 mm, sparsely glandular, bracts at remaining nodes 3, forming an orbiculate to somewhat triangular perfoliate disk mostly 1-2.5 cm across, glabrous or glandular, with awn one to three millimeter terminal bracts. The peduncles are erect, stout, at proximal nodes, though they are sometimes absent. Involucres are two to five millimeters, glabrous or sparsely glandular abaxially, sporting four teeth and awns are reddish, measuring two to three millimeters. Theplants sprout five to ten perianth white or yellowish green to pink, flowers. The tepals are monomorphic, lanceolate to ovate. The filaments mesure one to 1.5 millimeters that papillate basally. The anthers are pink to red and oval. The achenes are dark brown to maroon.
Oxytheca perfoliata is a food plant for the desert metalmark butterfly (Apodemia mormo deserti).

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