The grass genera of the world
~ Uniola (U. condensata and U. virgata)
Habit, vegetative morphology. Perennial (robust); caespitose. Culms 100–200 cm high; herbaceous. Plants unarmed. Leaf blades attenuated from about 8 mm wide; narrow; flat, or rolled (involute); without abaxial multicellular glands; not pseudopetiolate; without cross venation.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches; contracted (the stiff branches narrowly ascending). Primary inflorescence branches numerous. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes slender; persistent. Spikelets secund (conspicuously on one side of the rachis, usually closely imbricate); biseriate; shortly pedicellate; imbricate.
Female-fertile spikelets. Spikelets 1.5–7 mm long; oblong, or elliptic; compressed laterally; falling with the glumes; not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret.
Glumes present; two; very unequal (the upper longer); shorter than the adjacent lemmas; hairless; pointed (acuminate); awnless; carinate; similar. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets, or both distal and proximal to the female-fertile florets (?). Spikelets with proximal incomplete florets. The proximal incomplete florets 1–3 (?); sterile. The proximal lemmas awnless; 5 nerved; exceeded by the female-fertile lemmas; similar in texture to the female-fertile lemmas.
Female-fertile florets 3–6. Lemmas acuminate; not becoming indurated (firm, smooth, shining); entire; pointed; awnless, or mucronate (?); carinate (compressed-keeled, especially above); 5 nerved. Palea present; awnless, without apical setae. Lodicules present; free; fleshy; glabrous. Stamens 3. Stigmas 2.
Fruit, embryo and seedling. Fruit longitudinally grooved, or not grooved; not noticeably compressed, or trigonous. Hilum short. Pericarp fused (?). Embryo large; with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.
First seedling leaf with a well-developed lamina. The lamina narrow; erect to curved.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (but obviously distinguished only by the distribution of stomatal bands). 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 (but scarce, and no good examples seen); chloridoid-type (?). Stomata common; 24–27 microns long. Subsidiaries low dome-shaped. Intercostal short-cells common; in cork/silica-cell pairs (some solitary); silicified. Intercostal silica bodies absent; rounded and crescentic. Costal short-cells predominantly paired (some solitary). Costal silica bodies present throughout the costal zones; rounded, or saddle shaped (or rectangular), or crescentic; not sharp-pointed.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions present. Maximum number of extension cells 6–10. PCR cells with a suberised lamella, or without a suberised lamella. Mesophyll traversed by columns of colourless mesophyll cells (connected to abaxial sclerenchyma groups). Leaf blade with distinct, prominent adaxial ribs. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these linked with traversing columns of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures (in the large bundles). Sclerenchyma not all bundle-associated. The extra sclerenchyma in abaxial groups; abaxial-hypodermal, the groups isolated, or abaxial-hypodermal, the groups continuous with colourless columns.
Cytology. Chromosome base number, x = 10 (n = 20). 2n = 40.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): cf. Chloridoideae; Eragrostideae; Unioliinae (? - as a synonym). 2 species.
Distribution, phytogeography, ecology. Puerto Rico and South to Central America.
Xerophytic; species of open habitats; halophytic, or glycophytic.
References, etc. Leaf anatomical: this project.
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’.