Lintonia Stapf
Including Joannegria Chiov., Negria Chiov.
Habit, vegetative morphology. Perennial; caespitose, or rhizomatous and caespitose. Culms 20–90 cm high; herbaceous; branched above. Culm nodes glabrous. Culm internodes hollow. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear (tapered to a fine, acuminate tip); narrow; 2–6 mm wide; flat; without abaxial multicellular glands; without cross venation; persistent; an unfringed membrane (minutely ciliolate, with long hairs at the auricle positions); truncate; 1 mm long. Contra-ligule absent.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches; open; digitate, or non-digitate (L. brizoides). Primary inflorescence branches 2–8. Inflorescence espatheate (but often enveloped below by the sheath of the uppermost culm leaf); not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’. The racemes without spikelets towards the base. Spikelet-bearing axes sinuous, with very slender rachides; persistent. Spikelets solitary; somewhat secund, or not secund; biseriate, or not two-ranked; subsessile to pedicellate.
Female-fertile spikelets. Spikelets 4–11 mm long; plump, cuneate, or elliptic; adaxial; compressed laterally; disarticulating above the glumes; not disarticulating between the florets (the rachilla tough); with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (below the lowest floret), or hairless (between the upper florets); the rachilla extension with incomplete florets. Hairy callus present (i.e., below the lowermost floret). Callus on the lower floret short; blunt.
Glumes two; very unequal (G1 shorter); shorter than the spikelets; shorter than the adjacent lemmas; free; dorsiventral to the rachis; hairless; glabrous (the keel sometimes scabrous); pointed (the nerve slightly excurrent), or not pointed (slightly notched); awnless (sub-mucronate); carinate (slightly), or non-carinate (rounded on the back); similar (persistent, hyaline-membranous). 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 1–4; merely underdeveloped; shortly awned. Spikelets without proximal incomplete florets.
Female-fertile florets 2–4. Lemmas decidedly firmer than the glumes (tough and cartilaginous, at least in part); not becoming indurated; shortly incised; 2 lobed; not deeply cleft (emarginate or 2-toothed); awned. Awns 1; median; dorsal; from near the top; non-geniculate (curved); hairless (scabrid); much shorter than the body of the lemma to about as long as the body of the lemma; entered by one vein. Lemmas hairy (the hairs clavate and apiculate, in 5–6 longitudinal rows on the nerves); non-carinate (abaxially rounded); without a germination flap; 5–9 nerved; with the nerves non-confluent. Palea present; relatively long (about 3/4 the length of the lemma); entire, or apically notched (between the prolonged nerve tips); awnless, without apical setae, or with apical setae (comprising the short scabrid nerve-tips); thinner than the lemma; not indurated (hyaline); 2-nerved; 2-keeled (sharply complanate). Palea keels wingless; hairy (conspicuously ciliate). Lodicules present; 2; free; fleshy (cylindrical rather than cuneate); glabrous. Stamens 3; with free filaments (these attached at the base of the ovary, the androecium and gynoecium being borne on a short stipe between the lodicules). Anthers 1 mm long; not penicillate; without an apically prolonged connective. Ovary glabrous. Styles free to their bases. Stigmas 2; red pigmented (dark purple).
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (1.3–2.2 mm long); ellipsoid; strongly compressed dorsiventrally. Hilum short (elliptical). Pericarp free. Embryo large (about half the length of the fruit); not waisted.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae over-arching the stomata (at one end); consisting of one symmetrical projection per cell (to almost spherical). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type (large, with a relatively short basal cell and a hemispherical distal cell). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 18–21 microns long. Microhair basal cells 6 microns long. Microhairs (9–)11.4–12(–13.5) microns wide at the septum. Microhair total length/width at septum 1.5–2.2. Microhair apical cells 12–13.5 microns long. Microhair apical cell/total length ratio 0.6–0.75. Stomata common; 22.5–25.5 microns long. Subsidiaries mostly triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare; where detected, not paired. Intercostal silica bodies absent. Crown cells absent (and prickles at leaf margins only). Costal short-cells conspicuously in long rows (but the short-cells sometimes rather long). Costal silica bodies present in alternate cell files of the costal zones; saddle shaped; 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 both abaxially and adaxially. PCR sheath extensions absent. PCR cell chloroplasts centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Midrib conspicuous; having a conventional arc of bundles (large median, and 4 small bundles on each side); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (a few of the latter only, with small internal colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming ‘figures’. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Cytology. 2n = 30.
Taxonomy. Chloridoideae; main chloridoid assemblage.
Distribution, ecology, phytogeography. 2 species; tropical east Africa. Helophytic, or mesophytic; shade species, or species of open habitats; glycophytic. Savanna, heavy soils in seasonally wet places.
Paleotropical. African. Sudano-Angolan. Sahelo-Sudanian, Somalo-Ethiopian, South Tropical African, and Kalaharian.
References, etc. Leaf anatomical: this project; photos of L. nutans provided by R.P. Ellis.
Illustrations. • General aspect
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
