Family: Poaceae |
Mary E. Barkworth Plants usually perennial. Culms 7-600 cm, annual, not woody, often reddish or purple, particularly at the nodes, often branched above the base. Sheaths open; ligules usually scarious to membranous, ciliate or not; blades mostly well-developed, leaves subtending an inflorescence or an inflorescence unit often with reduced blades. Photosynthetic pathway NADP-ME; bundle sheaths single. Inflorescences terminal, frequently on both the culms and their branches, sometimes also axillary, usually of 1-many spikelike branches, these in digitate clusters of 1-13+ on a peduncle or attached, directly or indirectly, to elongate rachises, often partially to almost completely enclosed by the subtending leaf sheath at maturity, in some taxa axillary inflorescences composed of multiple-stalked pedunculate clusters of inflorescence branches subtended by a modified leaf;disarticulation usually in the branch axes beneath the sessile florets, the dispersal unit being a sessile floret, the internode to the next sessile floret, the pedicel, and the pedicellate spikelet (branches with disarticulating axes are termed rames in the following accounts), sometimes beneath the glumes, the branch axes remaining intact. Spikelets in unequally pedicellate pairs, sessile-pedicellate pairs, or triplets, or apparently solitary and sessile, pedicellate spikelets and sometimes the pedicels reduced or absent, triplets usually with 1 sessile and 2 pedicellate spikelets, terminal spikelet units on the branches often with 2 pedicellate spikelets even if the others have only 1 (all spikelet units with 2 sessile and 1 pedicellate spikelets in Polytrias). Spikelet pairsor triplets homogamous (spikelets in the unit sexually alike) or heterogamous (spikelets in the unit sexually dissimilar); spikelets of unequally pedicellate pairs usually homogamous and homomorphic; spikelets in sessile-pedicellate pairs or triplets usually heterogamous and heteromorphic; sessile spikelets usually bisexual; pedicellate spikelets usually smaller than the sessile spikelets, often staminate or sterile, sometimes absent. Spikelets usually with 2 florets (1 in Polytrias). Glumesexceeding and usually concealing the florets (excluding the awns), rounded or dorsally compressed, usually tougher than the lemmas; lower florets in bisexual or pistillate spikelets sterile or staminate, often reduced to a hyaline scale; upper floretsbisexual or pistillate, lemmas often hyaline, sometimes with an awn that exceeds the glumes; lodicules cuneate; anthers usually 3. Pedicels free or fused to the rachis internodes. Pedicellate spikelets variable, sometimes similar to the sessile spikelets, sometimes differing in sexuality and shape, sometimes missing. x = usually 9 or 10, or possibly 5 with 9 and 10 reflecting ancient polyploidy. The tribe Andropogoneae includes about 87 genera and 1060 species, of which 31 genera and 102 species have been found in the Flora region; some of these have not become established. The tribe is common in tropical and subtropical regions, particularly in areas with significant summer rains, such as the central plains of North America. Two of the grasses that used to dominate the prairies of central North America, Andropogon gerardii and Schizachyrium scoparium (Big and Little Bluestem, respectively), are member of the Andropogoneae. The reddish-purplish coloration that characterizes the culms and leaves of many Andropogoneae gives a striking aspect to grasslands (and lawns) dominated by its members. Members of the Andropogoneae differ from those of Paniceae in the reduced lemmas and paleas of their florets and, usually, in their paired, unequally pedicellate spikelets, disarticulating inflorescence branches (rames), and the manner in which these branches are aggregated into inflorescences. Unequally pedicellate spikelet pairs are found in many other tribes, but they are more common, and the pedicels more strikingly unequal in length, in the Andropogoneae. Recent molecular work supports recognition of the tribe with one modification of its traditional limits, the incorporation of Arundinella and Tristachya (Kellogg 2000). There is less agreement on the tribes internal structure and its relationship to the Paniceae (Clayton and Renvoize 1986; Kellogg 2000; Spangler 2000; Guissani et al. 2001).
Inflorescence Structures
Inflorescence Structure Welker, C.A.D., M.R.McKain, M.C.Estep, R.S.Pasquet, G.Chipabika, B.Pallangyo, and E.A.Kellogg (2020) Phylogenomics enables biogeographic analysis and a newsubtribal classication of Andropogoneae(Poaceae — Panicoideae). Journal of Systematics and Evolution 58:1003 - 1030. doi: 10.1111/jse.12691 |