Family: Poaceae |
Grass Phylogeny Working Group 25: 297 Plants usually perennial, sometimes annual, if perennial, cespitose, rhizomatous or stoloniferous. Culms usually solid, rarely hollow. Leaves distichous; sheaths usually open; abaxial ligules usually absent, sometimes represented by a line of hairs; auricles usually absent; adaxial ligules of hairs or membranous and ciliate; blades not pseudopetiolate; mesophyll not radiate; adaxial palisade layer absent; fusoid cells absent; arm cells absent; kranz anatomy absent; midribs simple, usually with 1 vascular bundle (an arc of bundles in Cortaderia); adaxial bulliform cells present or no; stomata usually with dome-shaped or parallel-sides subsidary cells, rarely these slightly triangular or high domedl bicellular microhairs usually present, distal cells long, narrow; pappillae usually absent. Synflorescences ebracteate (subtending leaf somewhat spatheate in Urochlaena), usually paniculate, sometimes racemose or spicate, occasionally a single spiklet; disarticulation usually above the glumes and below the florets, sometimes below the glumes or in the culms. Spikelets bisexual or unisexual, with 1-7(-20) bisexual or pistillate florets, distal florets often sterile or staminate; rachilla extension present. Glumes 2, usually equal, (1-) 3 (-7) veined, usually exceeding the distal florets; florets laterally compressed; lemmas firmly membranous to coriaceous, 3-9-veined, rounded across the back glabrous or with non-uncinate hairs, these sometimes in tufts or fringes, lemma apices shortly to deeply bilobed, lobes often setacaeous; midveins extended as awns; awns usually geniculate, basal segment, often flat and twisted; paleas well developed, sometimes short relative to the lemmas; lodicules 2, usually free, usually fleshy, rarely with a membranous apical flap, glabrous or ciliate, often with microhairs, sometimes heavily vascularized; anthers 3; ovaries usually glabrous, rarely with apical hairs; haustorial synergids present, sometimes weakly developed; styles 2, baes usually widely separated. Caryopses falling separately from the lemmas and pales; hila punctate or long-linear; embryos lare or small relative to the caryopses; endosperm hard; starch grains usually compound; epiblasts absent; scutellar cleft present; mesocotyl internode elongated; embryonic leaf margins usually meeting, sometimes overlapping. x = 6, 7, 9. The Danthonoideae include only one tribe, the Danthoinieae. The combination of hautorial synergids, ciliate ligules, elongated embryo mesocotyls, and C3 photosyntheses distinguishes the Danthonioideae from all other subfamilies of the Poaceae. Unfortunately, only the ligule character is useful in the field. Consequently, family keys go directly to genera anr/or rely on a combination of features that work in a particular region. |