Grass Genera of the World

L. Watson and M. J. Dallwitz


Dallwatsonia B.K. Simon

Named for M.J.Dallwitz and L.Watson.

Habit, vegetative morphology. Perennial. Culms 40–130 cm high; herbaceous; branched above; 7 noded. Leaf blades linear, or linear-lanceolate; a fringed membrane.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence of spicate main branches, or paniculate (the main axis to 22 cm long, the primary branches to 6 cm, the spikelet bearing branches reduced to 2-several spikelets); non-digitate. Primary inflorescence branches inserted all around the main axis. Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. The racemes spikelet bearing to the base. Spikelet-bearing axes persistent. Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; more or less paired; secund to not secund (the spikelet bearing branches on two sides of the three-sided rachis); pedicellate (the pedicels 0.1–4 mm long). Pedicel apices cupuliform. Spikelets not imbricate; somewhat consistently in ‘long-and-short’ combinations; unequally pedicellate in each combination.

Female-fertile spikelets. Spikelets 3.5–4 mm long; elliptic, or lanceolate; adaxial; somewhat compressed laterally; falling with the glumes; not disarticulating between the florets; with conventional internode spacings. The upper floret not stipitate. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus absent.

Glumes two; very unequal (the lower much shorter); (the upper) consistently somewhat shorter than the spikelets; shorter than the adjacent lemmas; hairless; glabrous; pointed; awnless; non-carinate (but with raised nerves); very dissimilar (membranous, the lower ovate and much shorter, the upper lanceolate and almost as long as the L1). Lower glume 0.3–0.5 times the length of the upper glume; shorter than the lowest lemma; much shorter than half length of lowest lemma; convex on the back; relatively smooth; 5 nerved. Upper glume not saccate; 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets reduced (no more than half the lemma length, linear or lanceolate, hyaline); not becoming conspicuously hardened and enlarged laterally. The proximal incomplete florets sterile. The proximal lemmas lanceloate, membranous, resembling the upper glume; awnless; 5 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas to similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas lanceolate; not saccate; similar in texture to the glumes to decidedly firmer than the glumes (membranous to very thinly cartilaginous); smooth; not becoming indurated; white in fruit; entire; pointed; not deeply cleft; not crested; awnless; hairless; glabrous; non-carinate (rounded on the back); having the margins lying flat on the palea; with a clear germination flap; 5–7 nerved (the median lacking or basal only in the material seen); with the nerves non-confluent. Palea present; relatively long; gaping; entire; awnless, without apical setae; textured like the lemma; not indurated; 2-nerved; keel-less. Palea back glabrous. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers 1.4–2 mm long; not penicillate; without an apically prolonged connective. Ovary glabrous; without a conspicuous apical appendage. Styles free to their bases; free. Style bases widely separated. Stigmas 2.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (the walls of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type (broad, almost balanoform); 50–55 microns long; about 10 microns wide at the septum. Microhair total length/width at septum 5–5.5. Microhair apical cells 35–40 microns long. Microhair apical cell/total length ratio 0.7–1. Stomata common; 15–20 microns long. Subsidiaries non-papillate; dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs (mostly), or not paired (some solitary); silicified and not silicified. Intercostal silica bodies mostly more or less cross-shaped. With a few small intercostal prickles. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; ‘panicoid-type’; short to medium dumb-bell shaped, or nodular (a few only).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll seemingly Isachne-type (at least in places); not traversed by colourless columns; without fusoids (but most of the intercostal zones with a well defined aerenchymatous region in the middle). Leaf blade ‘nodular’ in section to adaxially flat. Midrib conspicuous (the keel large and abaxially prominent); having a conventional arc of bundles (the large median accompanied on either side by several small laterals); with colourless mesophyll adaxially. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all or most of the lateral bundles); forming ‘figures’ (some of the configurations somewhat I-shaped). Sclerenchyma all associated with vascular bundles.

Taxonomy. Panicoideae; Panicodae; Paniceae.

Distribution, ecology, phytogeography. 1 species; Queensland. Helophytic; glycophytic.

Australian. North and East Australian. Tropical North and East Australian.

References, etc. Morphological/taxonomic: B.K. Simon 1992. Leaf anatomical: this project.

Special comments. Fruit data wanting.

Illustrations. • General aspect, inflorescence, spikelet and florets. • Spikelet. Dallwatsonia felliana. • Abaxial epidermis of leaf blade. Dallwatsonia felliana. • Abaxial epidermis of leaf blade. Dallwatsonia felliana. • Abaxial epidermis of leaf blade. Dallwatsonia felliana.


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