The grass genera of the world
Including Antoschmidtia Boiss.
Habit, vegetative morphology. Annual, or perennial (usually viscid); caespitose to decumbent. Culms 15–100 cm high; herbaceous; branched above. Culm nodes hairy, or glabrous. Culm internodes hollow. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate; with auricular setae. Leaf blades linear to linear-lanceolate; broad, or narrow; 4–13 mm wide; flat, or rolled; exhibiting multicellular glands abaxially (at the base of macrohairs). The abaxial leaf blade glands intercostal. Leaf blades not pseudopetiolate; without cross venation; persistent. Ligule a fringe of hairs; truncate. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; subsessile to pedicellate.
Female-fertile spikelets. Spikelets 7–10 mm long; slightly compressed laterally; disarticulating above the glumes; not disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus present. Callus short.
Glumes two; very unequal to more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; hairless; pointed; awnless; slightly carinate, or non-carinate; similar (lanceolate, membranous, usually green or grey). Lower glume about 0.6–0.7 times the length of the upper glume; much exceeding the lowest lemma; 7–11 nerved. Upper glume 7–11 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1, or 2; merely underdeveloped; awned.
Female-fertile florets 3–9. Lemmas decidedly firmer than the glumes (subleathery); not becoming indurated; incised; 6 lobed; deeply cleft; awned. Awns 5 (one awn from each sinus, and the lobes sometimes mucronate as well); median and lateral; the median similar in form to the laterals; non-geniculate; hairless (scabrid); about as long as the body of the lemma; entered by one vein. The lateral awns about equalling the median. Lemmas hairy (villous below); non-carinate (dorsally rounded); without a germination flap; 9 nerved; with the nerves non-confluent. Palea present; relatively long (longer than the body of the lemma); tightly clasped by the lemma; entire (pointed); awnless, without apical setae; thinner than the lemma; not indurated; 2-nerved; 2-keeled. Palea keels wingless; hairy (stiffly ciliate). Lodicules present; 2; fleshy; ciliate (sometimes glandular), or glabrous. Stamens 3. Anthers 3–4 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (about 2.5 mm long); ellipsoid; compressed dorsiventrally. Hilum short. Pericarp fused. Embryo large; waisted; with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Ovule, embryology. Outer integument covering no more than the chalazal half of the ovule. Inner integument continuous, the micropyle constricted. Synergids not haustorial; without large, globular starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; Enneapogon-type (very variable in size, at least in S. pappophoroides). Microhair apical cell wall thinner than that of the basal cell but not tending to collapse. Microhairs (54–)81–360(–426) microns long. Microhair basal cells 45–150–405 microns long. Microhairs (5.4–)6–9.6(–10.5) microns wide at the septum. Microhair total length/width at septum 10–34.3. Microhair apical cells (19.5–)24–51(–63) microns long. Microhair apical cell/total length ratio 0.15–0.36. Stomata common; (21–)24–30(–33) microns long. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (mainly solitary); not silicified. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; panicoid-type; cross shaped, dumb-bell shaped, and nodular; not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines uneven. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (between each bundle pair); in simple fans (the median cells deeply penetrating), or associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (most bundles with strands only), or present (a few). Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. Female-fertile lemmas 6-lobed and 5-awned, with an awn arising between each pair of lobes.
Cytology. Chromosome base number, x = 9. 2n = 36.
Classification. Watson & Dallwitz (1994): Chloridoideae; Pappophoreae. Soreng et al. (2015): Chloridoideae; Eragrostideae; Cotteinae. 2 species.
Distribution, phytogeography, ecology. Tropical and southern Africa, Cape Verde Is., Pakistan.
Xerophytic; species of open habitats; glycophytic. Woods and bushland, on dry sandy soils.
References, etc. Leaf anatomical: this project; photos of S. kalihariensis and S. pappophoroides provided by R.P. Ellis.
Illustrations. • General aspect (S. pappophoroides): Gibbs Russell et al., 1990. • S. pappophoroides, abaxial epidermis of leaf blade: this project. Enneapogon-type microhairs: one exhibiting its translucent apical cell (top left)
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The 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. Version: 13th November 2017. delta-intkey.com/grass’.