''Hopia obtusa'' is a species of

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

commonly known as vine mesquite. This plant was treated as ''Panicum obtusum'' until recently when more molecular and genetic material revealed new information about it. ''Hopia obtusa'' is now placed in the

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

''Hopia''.

Description

''Hopia obtusa'' is a perennial grass with stems up to tall. It has long, creeping

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

s or shallow rhizomes with swollen, villous nodes. The culms are usually in small, compressed, glaucous clumps that are either erect or decumbent. Nodes are hairy lower on the plant but glabrous higher up. The sheath is pubescent to pilose lower on the plant but glabrous higher up. It has membranous truncate, irregularly denticulate

ligule A ligule (from "strap", variant of ''lingula'', from ''lingua'' "tongue") is a thin outgrowth at the junction of leaf and leafstalk of many grasses (Poaceae) and sedges. A ligule is also a strap-shaped extension of the corolla, such as that of a ...

s that are big. Leaf blades are long and wide; they are ascending, firm, glaucous, sparsely pilose near the base, often scabrous on the margins, and involute towards the tips. The

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are of ...

s are long and wide. The panicle has 2 to 6 spikelike, erect, puberulent, and 3-angled branches. The ultimate branchlets are one-sided. The

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

s are paired and congested. Some spikelets are on short pedicels that are , while others are on longer pedicels . Spikelets are long, ellipsoid, terete to slightly laterally compressed, glabrous, and obtuse. The lower glumes are about 3/4 as long as the spikelet and are 5- or 7-veined. Upper glumes and lower lemmas equal the spikelet's length and are 5– to 9-veined. The lower florets are

staminate The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

with its lower paleas long. The upper florets are puberulent at the bases and apices. Flowering is from May through October.

Habitat and ecology

''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. It is a larval host to the dotted roadside skipper.The Xerces Society (2016), ''Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects'', Timber Press.

References

{{Taxonbar, from1=Q15963714, from2=Q5900564 Panicoideae Monotypic Poaceae genera Flora of the United States Flora of Mexico