The grass genera of the world
Including Diplachne barbata Hack.; Gouinia barbata (Hack.) Swallen
Habit, vegetative morphology. Perennial; caespitose. Culms 60–90 cm high; herbaceous; unbranched above; 2–4 noded. Culm nodes hidden by leaf sheaths. Young shoots intravaginal. Leaves mostly basal; non-auriculate. Leaf blades linear; narrow; 1–2 mm wide (10–30 cm long); flat, or rolled (convolute or involute); without cross venation. Ligule a fringed membrane. Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite.
Inflorescence. Inflorescence of spicate main branches (2–30 cm long, the lower branches 10–12 cm long, the rachis not grooved). Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. The racemes spikelet bearing to the base. Spikelet-bearing axes persistent. Spikelets solitary; shortly pedicellate (the pedicels 0.5–3 mm long); imbricate to not imbricate.
Female-fertile spikelets. Spikelets 9–11 mm long; cuneate, or lanceolate; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (sulcate-triangular in section towards the tip). Hairy callus present. Callus pointed.
Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; hairless; glabrous; pointed; awnless; similar (lanceolate, memranous to papery). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1–2 (?); merely underdeveloped; awned. Spikelets without proximal incomplete florets.
Female-fertile florets 4–6. Lemmas linear-lanceolate, laterally flattened; similar in texture to the glumes (membranous to papery); not becoming indurated; incised; shortly 2 lobed; not deeply cleft; awned. Awns 1; median; from a sinus; non-geniculate; straight, or flexuous; hairless (antrorsely scabrid); about as long as the body of the lemma to much longer than the body of the lemma (2–7 mm long); entered by one vein. Awn bases not twisted; not flattened. Lemmas hairy (scabrid on the median nerve, the lateral nerves pectinate-ciliate, pilose at the base and between the nerves); carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present; relatively long, or conspicuous but relatively short (4–4.5 mm long); entire; awnless, without apical setae; textured like the lemma; not indurated; 2-nerved; 2-keeled. Palea back glabrous. Palea keels scabrous. Stamens 3. Anthers about 1 mm long (yellow). Ovary apically glabrous (?). Stigmas 2 (?).
Fruit, embryo and seedling. Fruit small (about 3 mm long); narrowly ellipsoid; compressed laterally and trigonous. Hilum short.
Abaxial leaf blade epidermis. Papillae absent. Intercostal zones with typical long-cells. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent (chloridoid type present adaxially). Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs and not paired. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present and well developed; panicoid-type; dumb-bell shaped.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4. The anatomical organization conventional. XyMS+. PCR sheath outlines seemingly even. PCR sheath extensions absent. Mesophyll with radiate chlorenchyma; not Isachne-type; without fusoids. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only; without colourless mesophyll adaxially.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Gouiniinae. 1 species (S. barbata).
Distribution, phytogeography, ecology. North eastern Brazil.
Species of open habitats. Coastal dunes and sandy soils.
References, etc. Morphological/taxonomic: Ortíz 1991. Leaf anatomical: Ortíz 1991.
Special comments. Fruit data wanting. Anatomical data somewhat wanting.
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’.