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The grass genera of the world

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

Jansenella Bor

Habit, vegetative morphology. Annual. Culms herbaceous; unbranched above. Leaves not basally aggregated. Leaf blades lanceolate; narrow; 3–7 mm wide (to about 3.5 cm long); slightly cordate; flat; without cross venation. Ligule an unfringed membrane.

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

Inflorescence. Inflorescence paniculate; contracted; spicate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets paired (usually), or in triplets (rarely); not secund.

Female-fertile spikelets. Spikelets 6–9 mm long; purplish; compressed laterally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short; blunt.

Glumes two; very unequal; (the upper) long relative to the adjacent lemmas; hairless; pointed; awned (aristulate, the points 1–2 mm long), or awnless. Lower glume 3 nerved. Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets (or the L1 occasionally hermaphrodite). The proximal incomplete florets when present, 1; paleate. Palea of the proximal incomplete florets fully developed (two keeled, narrowly two winged). The proximal incomplete florets male, or sterile (or even female). The proximal lemmas awned (with a short, dorsal capillary awn); 5–9 nerved; decidedly exceeding the female-fertile lemmas (similar to G2); less firm than the female-fertile lemmas (membranous, leathery); not becoming indurated.

Female-fertile florets 1(–2). Lemmas decidedly firmer than the glumes; becoming leathery; incised; 2 lobed; deeply cleft; awned. Awns 1, or 3; median, or median and lateral (the two lobes aristulate); the median different in form from the laterals (if laterals considered present); from a sinus; geniculate. The lateral awns shorter than the median. Lemmas hairy. The hairs in tufts (these thick, near the margins at the bases of the lobes); in transverse rows (transversely bearded with brown hairs in the lower half). Lemmas non-carinate; 7–9 nerved. Palea present; relatively long; apically notched; 2-nerved; 2-keeled. Palea keels winged (and with peculiar unicellular, turgid hairs between the keels). Lodicules present; 2; free; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2.

Fruit, embryo and seedling. Fruit small (1.3 mm long). Hilum short. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Microhairs present; panicoid-type. Costal silica bodies ‘panicoid-type’; dumb-bell shaped.

Transverse section of leaf blade, physiology. Supposedly C3 (but needing further study: certainly the anatomical drawings of Türpe (1970) show neither ‘circular cells’ nor the expected small bundles); XyMS– (from Türpe’s detailed drawings, which if accurate reveal this as the only known C3 XyMS- combination). Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib not readily distinguishable.

Cytology. 2n = 20.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Arundinelleae. Soreng et al. (2015): Panicoideae. 1 species.

Distribution, phytogeography, ecology. India, Burma.

Mesophytic. Moist places in hills.

References, etc. Leaf anatomical: Metcalfe 1960, Türpe 1970.


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’.

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