All Floras      Advanced Search
FOC Vol. 22 Page 570 Login | eFloras Home | Help
FOC | Family List | FOC Vol. 22 | Poaceae

28. Poaceae Tribe ANDROPOGONEAE

高粱族 gao liang zu

Authors: Shou-liang Chen, Bi-xing Sun, Sylvia M. Phillips & Stephen A. Renvoize

Annual or perennial. Leaf blades linear, rarely lanceolate or filiform; ligule membranous, rarely ciliate. Inflorescence composed of fragile (infrequently tough) racemes, these arranged in a terminal panicle with elongate central axis, or more frequently subdigitate, paired or solitary, often axillary, subtended by spathes and spatheoles and gathered into a compound panicle. Racemes usually bearing paired spikelets (with a terminal triad), rarely spikelets single or in threes, usually one spikelet of a pair sessile and the other pedicelled, infrequently both pedicelled; rachis fracturing at maturity beneath each spikelet pair. Spikelets of a pair alike or more often dissimilar in shape and sex, when dissimilar sessile spikelet bisexual or female, pedicelled spikelet male or barren, rarely pedicelled spikelet vestigial or absent and sessile spikelet then apparently single; sometimes 1 or more of lowermost pairs in raceme infertile, resembling pedicelled spikelets, persistent (homogamous pairs); rachis internodes and pedicels filiform, linear or thickened, sometimes very stout and partially enclosing spikelet, falling with adjacent sessile spikelet, pedicelled spikelet falling separately; callus at base of sessile spikelet obtuse to pungent. Sessile spikelet with 2 florets, usually dorsally compressed; glumes enclosing florets, hardened, lower glume facing outward, very variable, convex or 2-keeled, upper glume boat-shaped, fitting between internode and pedicel; lower floret male or barren, lower lemma hyaline, 2-keeled, lower palea suppressed when floret barren; upper floret fertile, upper lemma hyaline, narrow, entire or 2-toothed, awnless or bearing a geniculate awn with twisted column, upper palea short or absent. Pedicelled spikelet usually lanceolate, papery, often smaller than pedicelled spikelet; pedicel resembling rachis internode, rarely absent or fused to internode. Leaf anatomy Kranz MS. x = 5, 9.

About 85 genera and ca. 1000 species: throughout the tropics, extending into warm-temperate regions; 41 genera (one or two introduced) and 204 species (42 endemic, seven or eight introduced) in China.

Members of this tribe can usually be readily recognized by their fragile racemes bearing paired spikelets, one sessile and the other pedicelled. The dispersal unit is thus composed of sessile spikelet, rachis internode, and pedicel (the pedicelled spikelet falls separately), all of which contribute to the protection of the seed and are frequently ornamented or modified.

In the more primitive members both spikelets of a pair are alike and fertile and are arranged in a terminal panicle. In most genera, however, the pedicelled spikelet has lost its fertility and differs in shape and texture from the sessile one. In some genera the pedicelled spikelet is much reduced, and in extreme cases its pedicel is reduced to a vestige or fused to the adjacent internode. The sessile spikelets then appear single, but the fragile rachis gives a good clue to the correct tribe.

Another trend apparent throughout the tribe is the reduction of the large, terminal inflorescence to a few digitate or paired racemes, often arising from the axils of specialized leaves with inflated sheaths and reduced blades (spathes). In the most complex genera the ultimate unit is a boat-shaped sheath without a blade (spatheole) subtending 1 or 2 short racemes, and by repeated branching many of these units are gathered into a leafy compound panicle.

The spikelets contain 2 florets, but this is not obvious as the florets are delicate and usually reduced. However, it is seldom necessary to dissect the spikelets in order to identify a member of Andropogoneae. The apex of the upper lemma and position of the awn are sometimes important for identification. If the awn is gently drawn out, the small lemma at its base can be examined with a lens.

See the drawings of Andropogoneae features on page 3 of this volume.

Key 2

1 Inflorescence with elongate central axis, longer than lowest raceme   (2)
+ Inflorescence of solitary or subdigitate racemes   (5)
2 (1) Lower glume papery, convex, the veins raised.   186 Spodiopogon
+ Lower glume membranous or leathery, the veins flat   (3)
3 (2) Raceme rachis fragile; 1 spikelet of the pair sessile.   187 Saccharum
+ Raceme rachis tough; all spikelets pedicelled   (4)
4 (3) Panicle loose; glumes cartilaginous to leathery.   188 Miscanthus
+ Panicle contracted or spikelike; glumes membranous.   189 Imperata
5 (1) Inflorescences axillary   (6)
+ Inflorescence terminal   (7)
6 (5) Inflorescence a solitary raceme; spikelets laterally compressed; upper glume with long fine awn.   192 Pogonatherum
+ Inflorescence of 2–4 subdigitate racemes; spikelets dorsally compressed; upper glume awn-pointed.   193 Eulaliopsis
7 (5) Spikelets in groups of 3, 2 sessile and 1 pedicelled.   194 Polytrias
+ Spikelets paired   (8)
8 (7) Culms rambling; leaf blades lanceolate; spikelets sparsely hairy; lower glume concave to grooved along median line.   195 Microstegium
+ Culms erect; leaf blades linear; spikelets conspicuously hairy; lower glume convex to flat or slightly concave   (9)
9 (8) Slender annuals.   191 Pseudopogonatherum
+ Robust perennials   (10)
10 (9) Raceme rachis tough, both spikelets of pair pedicelled.   188 Miscanthus
+ Raceme rachis fragile; 1 spikelet of pair sessile.   190 Eulalia

List of Keys

  • List of lower taxa


    Related Objects  
  • FOC22_28_Andropogoneae.pdf
  • PDF

  • Flora of China @
    Browse by
    Advanced Search

    Flora of China Home




     |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |