Grass Genera of the World

L. Watson and M. J. Dallwitz


Arundinella Raddi

From the Latin arundo (a reed) and -ella (diminutive suffix).

Including Acratherum Link, Brandtia Kunth, Calamochloe Reichenb., Goldbachia Trin., Riedelia Kunth, Thysanachne Presl

Habit, vegetative morphology. Annual, or perennial; mostly with tough, erect culms. Culms 30–150 cm high; herbaceous; branched above, or unbranched above. Culm nodes glabrous. Culm internodes solid, or hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; not setaceous (rigid); flat, or rolled; without cross venation; disarticulating from the sheaths, or persistent; rolled in bud; a fringed membrane (narrow); truncate.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (sterile spikelets, when present, very reduced).

Inflorescence. Inflorescence paniculate; open, or contracted; with capillary branchlets, or without capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary, or paired; not secund; pedicellate; consistently in ‘long-and-short’ combinations, or not in distinct ‘long-and-short’ combinations. The ‘shorter’ spikelets hermaphrodite, or sterile (sometimes reduced to a glume). The ‘longer’ spikelets hermaphrodite.

Female-fertile spikelets. Spikelets 1.5–8 mm long; compressed laterally; disarticulating above the glumes, or disarticulating above the glumes and falling with the glumes (at least sometimes both); always disarticulating between the florets (but not between the upper glume and the lower floret). 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; pointed; awned, or awnless; very dissimilar to similar (membranous to papery, G1 acute to mucronate, G2 often caudate). Lower glume 3 nerved. Upper glume 5 nerved. Spikelets with incomplete florets (or rarely both florets perfect). The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets fully developed (narrow, two keeled). The proximal incomplete florets male. The proximal lemmas awnless; 3–7 nerved; less firm than the female-fertile lemmas to similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1(–2). Lemmas similar in texture to the glumes to decidedly firmer than the glumes (membranous to thinly leathery); not becoming indurated; entire, or incised; when entire pointed, or blunt; when incised, 2 lobed; not deeply cleft (entire, emarginate or bilobed); awnless, or awned. Awns 1 (usually), or 3; median, or median and lateral (via capillary bristles from the lobes); the median different in form from the laterals (when laterals present); from a sinus; geniculate; hairless; much shorter than the body of the lemma to much longer than the body of the lemma; persistent. Lemmas hairless (scabrid or scabridulous); non-carinate; having the margins lying flat on the palea, or having the margins inrolled against the palea; with a clear germination flap; 1–7 nerved. Palea present; entire (narrow); awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Palea keels wingless (the margins sometimes auriculate below). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 1.5–2 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; white, or red pigmented, or brown.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small; compressed dorsiventrally, or not noticeably compressed. Hilum short. Embryo large; waisted. Endosperm hard; without lipid; containing compound starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.

Seedling with a long mesocotyl.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; (36–)38–60(–62) microns long. Microhair apical cells (18–)21–42(–44) microns long. Microhair apical cell/total length ratio 0.56–0.67. Stomata common. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies tall-and-narrow, or crescentic. Costal short-cells predominantly paired. Costal silica bodies rounded (e.g. A. nepalensis), or crescentic (sometimes), or ‘panicoid-type’ (commonly); when panicoid type, cross shaped to dumb-bell shaped.

Transverse section of leaf blade, physiology. C4. The anatomical organization conventional, or unconventional. Organization of PCR tissue when unconventional Arundinella type. Biochemical type NADP–ME (A. nepalensis); XyMS–. PCR sheath outlines uneven. PCR sheath extensions present. Maximum number of extension cells 1. PCR cells with a suberised lamella. PCR cell chloroplasts ovoid; with reduced grana (rudimentary); centrifugal/peripheral. Mesophyll with radiate chlorenchyma; exhibiting ‘circular cells’, or without ‘circular cells’. Midrib conspicuous; with one bundle only, or having a conventional arc of bundles. Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Culm anatomy. Culm internode bundles in one or two rings.

Phytochemistry. Leaf blade chlorophyll a:b ratio 4.45–4.51.

Cytology. Chromosome base number, x = 7, 10, 12, and 14. 2n = 14, 20, 28, 36, and 56. Chromosomes ‘small’.

Taxonomy. Panicoideae; Panicodae; Arundinelleae.

Distribution, ecology, phytogeography. 55 species; in warm regions. Commonly adventive. Helophytic to mesophytic; species of open habitats; glycophytic. Marshy places, riverbanks and rocky slopes.

Holarctic, Paleotropical, Neotropical, Cape, and Australian. Boreal. African, Madagascan, and Indomalesian. Euro-Siberian and Eastern Asian. Saharo-Sindian, Sudano-Angolan, and West African Rainforest. Indian, Indo-Chinese, Malesian, and Papuan. Caribbean, Venezuela and Surinam, Central Brazilian, Pampas, and Andean. North and East Australian. Siberian. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African. Tropical North and East Australian.

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia coronata. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae — Tilletia. Ustilaginaceae — Sorosporium, Sphacelotheca, and Ustilago.

Economic importance. Significant weed species: A. bengalensis, A. leptochloa (in North America). Important native pasture species: A. setosa.

References, etc. Leaf anatomical: Metcalfe 1960; this project.

Illustrations. • General aspect. • General aspect. • Spikelets. Arundinella nepalensis. • Spikelet. Arundinella nepalensis. Female-fertile floret (awned lemma) to the left. • Abaxial epidermis of leaf blade. Arundinella nepalensis. • Abaxial epidermis of leaf blade. • Transverse section of leaf blade. Arundinella nepalensis. • Transverse section of leaf blade. Arundinella nepalensis. Fluorescent labelled RuBISCO, showing isolated PCR cells. • Transverse section of leaf blade. Arundinella nepalensis. Fluorescence image


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).

Index