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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Hubbardia Bor

Named for C.E. Hubbard, distinguished agrostologist.

Habit, vegetative morphology. Delicate annual; stoloniferous. Culms herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades narrowly elliptic; flimsy; relatively broad; 3–7 mm wide (and about 1.5–4 cm long); flat; without cross venation. Ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence paniculate (small, scanty, terminating the leafy branches); open; with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; not in distinct ‘long-and-short’ combinations.

Female-fertile spikelets. Spikelets unconventional (said to have two lemmas, both lacking paleas); 2.7 mm long; not noticeably compressed to compressed dorsiventrally; disarticulating above the glumes (the glumes persistent); not disarticulating between the florets. Rachilla terminated by a female-fertile floret (?). Hairy callus absent.

Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; hairless; awnless; non-carinate (lanceolate, round-backed); similar (thinly membranous). Lower glume 5–7 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas lanceolate; awnless; 7–9 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas not becoming indurated (membranous); entire; pointed, or blunt; awnless; hairless; non-carinate; 7–9 nerved. Palea absent (unless the ‘L2’ is a many-nerved palea). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small (1.5 mm long); fusiform; compressed dorsiventrally. Hilum short (very shortly linear). Embryo large (about a third of the fruit length). Endosperm containing compound starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Intercostal zones exhibiting many atypical long-cells. Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs absent (but present adaxially); panicoid type. Stomata absent or very rare. Intercostal short-cells absent or very rare. Costal silica bodies acutely-angled (cuboid); sharp-pointed (square to rectangular).

Transverse section of leaf blade, physiology. C3 (seemingly with only two layers of mesophyll, the cells of upper layer irregularly lobed, those of the lower forming a palisade).

Special diagnostic feature. Plants of wet places, the leaves remarkably thin and delicate.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Isachneae. Soreng et al. (2015): Micrairoideae; Hubbardieae. 1 species (H. heptaneuron).

Distribution, phytogeography, ecology. Southern India.

Helophytic (discovered in wet soil and high humidity, in the spray from a waterfall).

References, etc. Leaf anatomical: Clifford 1967.

Special comments. Extinct?.

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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: 11th December 2017.’.