Ptilagrostis Griseb.
From the Greek ptilo (down, as in feather) and agrostis (forage grass), alluding to pilose awns.
Sometimes referred to Stipa
Habit, vegetative morphology. Perennial; caespitose. Culms (5)1060 cm high; herbaceous; branched above, or unbranched above (?); (1)23 noded. Culm nodes hairy, or glabrous (?). Culm internodes solid, or hollow (?). Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear; very narrow; 0.20.9 mm wide (less than 0.5 mm when dry); setaceous (filiform, twisting when dried); folded, or rolled; without cross venation; persistent; once-folded in bud; an unfringed membrane; truncate, or not truncate; 0.23 mm long. Contra-ligule present, or absent (?).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets; inbreeding; exposed-cleistogamous, or chasmogamous (?); with hidden cleistogenes, or without hidden cleistogenes (?). The hidden cleistogenes (if present) in the leaf sheaths (?).
Inflorescence. Inflorescence few spikeleted to many spikeleted; paniculate; not deciduous; open, or contracted; with capillary branchlets (?); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3.47.5 mm long; compressed laterally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short (0.20.8 mm long); blunt.
Glumes two; more or less equal (subequal); slightly exceeding the spikelets, or about equalling the spikelets; long relative to the adjacent lemmas (equalling to slightly exceeding them); hairless; glabrous; pointed to not pointed (rounded, acute, or abruptly, briefly acuminate); awnless; non-carinate; similar (firmly membranous to hyaline). Lower glume (0)1 nerved, or 3 nerved, or 5 nerved (cf. Tsvelev 1976, Freitag 1985). Upper glume (0)1 nerved, or 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas lanceolate to ovate-lanceolate; convolute to not convolute (not concealing the palea); not saccate; without a crown; decidedly firmer than the glumes; with oval to rectangular abaxial epidermal silica bodies; not becoming indurated (membranous to leathery); dark brown in fruit; incised; 2 lobed; not deeply cleft; awned. Awns 1; median; from a sinus; geniculate (or sometimes bi-geniculate); long-plumose (usually, constituting a supposed distinction from Achnatherum), or hairless to hairy (P. kingii); much longer than the body of the lemma (742 mm long); entered by several veins (?); persistent (and without a basal articulation). Awn bases twisted. Lemmas hairy (the pubescence diffuse, confined to the lower part, or denser there); non-carinate (terete); having the margins lying flat on the palea; without a germination flap; (1)3(5) nerved. Palea present; relatively long (about equalling the lemma); tightly clasped by the lemma; not prow-tipped; entire (the tip flat and rounded); awnless, without apical setae; textured like the lemma; not indurated; 2-nerved (the veins falling short of the apex); keel-less. Palea back hairy. Lodicules present; 3. Third lodicule present. Lodicules free; membranous (stipoid, the third somewhat different); ciliate (e.g. P. mongholica), or glabrous; not toothed; heavily vascularized. Stamens 3. Anthers 0.43.3 mm long; penicillate, or penicillate to not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.73.3 mm long); linear, or fusiform; not grooved; compressed laterally. Hilum long-linear. Embryo small; not waisted. Endosperm hard; without lipid; containing only simple starch grains, or containing compound starch grains (?). Embryo with an epiblast (the epiblast short, truncate); without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Seedling with a short mesocotyl, or with a long mesocotyl (?). First seedling leaf with a well-developed lamina. The lamina narrow; erect.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous, or lacking.
Transverse section of leaf blade, physiology. C3; XyMS+. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles, or not all bundle-associated. The extra sclerenchyma of P. kingii in a continuous abaxial layer.
Cytology. Chromosome base number, x = 11. 2n = 22. 2 ploid. Chromosomes medium sized. Nucleoli disappearing before metaphase.
Taxonomy. Stipoideae; Stipeae.
Distribution, ecology, phytogeography. About 8 species; eastern U.S.S.R., western China, Himalayas, western North America. Helophytic to mesophytic (alpine-subalpine); species of open habitats. Alpine-subalpine.
Holarctic. Boreal. Euro-Siberian, Atlantic North American, and Rocky Mountains. European and Siberian. Canadian-Appalachian and Central Grasslands (?).
Rusts and smuts. Rusts Puccinia. Smuts from Tilletiaceae and from Ustilaginaceae.
Economic importance. Important native pasture species: All the species are pasture plants.
References, etc. Morphological/taxonomic: Tvelev 1976; Barkworth 1983; Freitag 1985; Barkworth and Everett 1987; Barkworth 1993.
Special comments. A Stipa segregate containing S. kingii, S. mongholica, etc., unsatisfactorily delimited from Achnatherum. See further comments under Stipa sensu lato. Anatomical data wanting.
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘Grass Genera of the World: Descriptions, Illustrations, Identification, and Information Retrieval; including Synonyms, Morphology, Anatomy, Physiology, Phytochemistry, Cytology, Classification, Pathogens, World and Local Distribution, and References.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).