Piptochaetium stipoides |
Poaceae subfam. pooideae |
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purple spear grass, stipoid ricegrass |
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Habit | Plants annual or perennial; sometimes matlike, sometimes cespitose, sometimes stoloniferous, sometimes rhizomatous. | |||||||||||||||||||||||||||||||||||||
Culms | 20-60 cm, erect to ascending; nodes 2-4, dark, glabrous. |
usually hollow, sometimes solid. |
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Sheaths | glabrous or hispidulous towards the collar; ligules 0.8-2 mm, glabrous, abaxial surfaces scabridulous, margins occasionally ciliate; blades (5)14-30 cm long, 0.2-0.4 mm wide, linear, glabrous or villous, margins scabridulous. |
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Leaves | distichous; sheaths usually open to the base, varying to closed for nearly their full length; auricles present or absent; abaxial ligules absent; adaxial ligules scarious or membranous, sometimes puberulent or scabridulous, usually not ciliate, cilia sometimes shorter than the base; pseudopetioles rarely present; blades usually linear, sometimes broadly so, venation parallel; cross sections non-Kranz, mesophyll nonradiate, adaxial palisade layer absent, fusoid and arm cells usually absent; midribs usually simple; adaxial bulliform cells present; stomates with parallel-sided subsidiary cells; epidermes usually lacking bicellular microhairs, sometimes with unicellular microhairs, papillae usually absent, when present, rarely more than 1 per cell. |
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Panicles | 4-15 cm long, 1.5-3 cm wide, with 10-70 spikelets; branches ascending, scabridulous; pedicels 1-11 mm, hispid. |
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Inflorescences | usually terminal, panicles, spikes, or racemes, usually ebracteate; disarticulation usually below the florets, sometimes below the glumes, at the rachis nodes, or at the inflorescence bases. |
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Spikelets | usually bisexual, infrequently unisexual or mixed, usually laterally compressed or not compressed, occasionally dorsally compressed, with 1-30 sexual florets, distal floret(s) often reduced, infrequently spikelets with 1-2 reduced or staminate basal florets and a single terminal sexual floret. |
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Glumes | subequal, 4-8.5 mm long, 1.5-2 mm wide, purple towards the base, glabrous, 5-veined, apices aristulate; florets 2.3-4(5) mm long, 0.8-2.3 mm thick, obovoid, globose to laterally compressed; calluses 0.5-0.6 mm, blunt, hairs white to golden tan; lemmas shiny, glabrous, striate, dark brown to black at maturity, wholly smooth to conspicuously verrucose or sharply papillose, at least distally, constricted below the crown; crowns well-developed, 0.6-1.6 mm wide, distal margins slightly to strongly revolute, inner surfaces densely covered with hooks and hairs; awns 15-25 mm, eccentric, twice-geniculate, tardily deciduous; paleas 2.5-5 mm; lodicules 2, linear; anthers about 0.5 mm. |
usually 2, upper or lower glumes sometimes absent, rarely both glumes absent; lemmas without uncinate hairs, awned or not, awns single, basal to apical; paleas usually well-developed, sometimes reduced or absent; lodicules 2(3), usually lanceolate and broadly membranous distally, rarely truncate and fleshy, usually not veined or obscurely veined, sometimes distinctly veined, sometimes ciliate; anthers (1, 2)3; ovaries glabrous or sometimes hairy distally, sometimes with an apical appendage; haustorial synergids absent; styles (1)2 (-4), bases close together, sometimes fused. |
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Caryopses | 1.5-2.5 mm, spherical to ellipsoid. |
hila linear, elliptic, ovate, or punctate; endosperm usually hard, sometimes soft or liquid, with or without lipids, starch grains compound or simple; embryos less than 1/2 the length of the caryopses; epiblasts usually present; scutellar cleft usually absent; mesocotyl internode usually absent; embryonic leaf margins overlapping, x = 7, 10. |
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2n | = unknown. |
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Piptochaetium stipoides |
Poaceae subfam. pooideae |
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Distribution |
CA
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Discussion | Piptochaetium stipoides is native to South America. There is one known population in the Flora region, in Marin County, California, which grows with P. setosum in a meadow adjacent to an old dirt road. The origin of the population is not known; it has been suggested that the seeds might have been brought in by birds, as the area was a bird refuge at one time. The Californian plants belong to Piptochaetium stipoides (Trin. & Rupr.) Hack. var. stipoides, which differs from the only other variety recognized by Cialdella and Arriaga (1998), P. stipoides var. echinulatum Parodi, in having lemmas that are mostly smooth as well as a less revolute crown. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The subfamily Pooideae includes approximately 3300 species, making it the largest subfamily in the Poaceae. It reaches its greatest diversity in cool temperate and boreal regions, extending across the tropics only in high mountains. The circumscription and relationships of tribes within the Pooideae are unsettled (see, for example, Catalan et al. 1997, 2004; Soreng and Davis 1998). In this flora, some previously recognized tribes have been combined with the Poeae. Recognition of some of these as subtribes is well supported; among these is the Hainardieae Greuter (which, at the subtribal level, is called the Parapholiinae Caro). Members of other traditional tribal groupings, such as the Aveneae Dumort., appear to be widely dispersed within the Poeae sensu lato. Further work will probably support the division of the expanded Poeae into additional tribes; there is as yet no clear indication as to what the boundaries of such tribes should be. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 166. | FNA vol. 24, p. 57. | ||||||||||||||||||||||||||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Stipeae > Piptochaetium | Poaceae | ||||||||||||||||||||||||||||||||||||
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Synonyms | P. stipoides var. purpurascens | |||||||||||||||||||||||||||||||||||||
Name authority | (Trin. & Rupr.) Hack. | Benth. | ||||||||||||||||||||||||||||||||||||
Web links |