Hopia

Vine Mesquite
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Subfamily:	Panicoideae
Tribe:	Paniceae
Genus:	Hopia
Species:	H. obtusa
Binomial name
Hopia obtusa (Kunth) Zuloaga & Morrone

Hopia obtusa, commonly known as Vine Mesquite. This plant was treated as Panicum obtusum until recently when more molecular and genitic material revealed new information about the plant(1). Hopia obtusa is now a monotypic species in the genus Hopia.

Description

Hopia Obtusa is a peranial grass. Culm may be anywhere between 20 to 80 cm tall. It has a long creeping rhizomes or shallow rhizomes with swollen, villous nodes. The culms are usually in small compressed glaucous clumps that are either erect or decumbent. Nodes pubecent lower on the plant but glaberous higher up. Sheath pubescent to pilose lower on the plant but glabrous higher up . It has membranous truncate irregularly denticulate ligules that are 0.2-2-mm. big. Leaf blades are 3-26 cm long and 2-7 mm wide; they are ascending, firm, glaucous, sparsely pilose near the base, often scabrous on the margins, and involute towards the apices. Panicles are 5-15 cm long and 0.8-1.5 cm wide. Panicle branches 2-6, spikelike, erect, puberulent, and 3-angled. The ultimate branchlets 1-sided. The pedicels paired and congested. Some spiklets on short pedicels that are 0.1-1 mm others on longer pedicels 1.5-2.5 mm. Spikelets 2.8-4.4 mm long, ellipsoid, terete to slightly laterally compressed, glabrous, and obtuse. Lower glumes about 3/4 as long as the spikelet and are 5- or 7-veined. Upper glumes and lower lemmas equaling the spikelets length and are 5-9-veined. The lower florets staminate with its lower paleas 2.5-3.5 mm long. The upper florets puberulent at the bases and apices.Flowering is from May through October. (2)

Habitat

Hopia obtusa grows in seasonally wet sand or gravel, especially on stream banks, ditches, roadsides, wet pastures, and rangeland. Its range extends from the southwestern United States to central Mexico. (2)

References

1. Zuloaga, Fernando O., Liliana M. Giussani, and Osvaldo Morrone. "Hopia, a New Monotypic Genus Segregated from Panicum (Poaceae)." Taxon 56 (2007): 145-56. Print.
2. "Hopia Description." Utah State University: Intermountain Herbarium. Web. 29 Nov. 2010. <http://herbarium.usu.edu/treatments/Hopia.htm>.