| # The grass genera of the world |

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

### Walwhalleya K.E. Wills & J.J. Bruhl

~ Panicum

Type species: W. pungens K.E. Wills & J.J. Bruhl.

Habit, vegetative morphology. Perennial; rhizomatous, or stoloniferous, or caespitose. Culms 10–100 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear, or linear to linear-lanceolate; narrow; 107–20 cm long, 1.9–7 mm wide; flat, or folded; not pseudopetiolate. Ligule an unfringed membrane; erose or entire, 0.7–4 mm long.

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

Inflorescence. Inflorescence paniculate; open (3–30 cm long); non-digitate. Rachides grooved to angled. Inflorescence espatheate. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate. Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 2.2–3.8 mm long; elliptic to lanceolate; compressed dorsiventrally; falling with the glumes; disarticulating between the florets; with conventional internode spacings, or with a distinctly elongated rachilla internode between the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; very unequal to more or less equal (the lower falling only somewhat shorter); (the upper) about equalling the spikelets; long relative to the adjacent lemmas; hairless; glabrous, or scabrous; more or less pointed; awnless; non-carinate; oblong, ovate, lanceolate or elliptic, more or less very dissimilar. Lower glume about 0.75 times the length of the upper glume; about equalling the lowest lemma, or much exceeding the lowest lemma; 3–7 nerved. Upper glume 7–9 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 to epaleate. Palea of the proximal incomplete florets if present, reduced. The proximal incomplete florets sterile. The proximal lemmas lanceolate, ovate or elliptic; awnless; prominently 7–9 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas; membranous or chartaceous, less firm than the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas elliptic; decidedly firmer than the glumes; muricate, not basally hyaline; becoming indurated; yellow in fruit; entire; more or less pointed (acuminate, acute or apically rounded); with the recurved apex apiculate or mucronate, not crested; awnless; hairless; glabrous; non-carinate; having the margins inrolled against the palea; with a clear germination flap; "obscurely nerved". Palea present; relatively long; apically notched; indurated. Palea back scabrous (finely muricate). Lodicules present; 2. Stamens 3.

Abaxial leaf blade epidermis. Microhairs supposedly present; panicoid-type.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C3; XyMS+. The lamina symmetrical on either side of the midrib.

Classification. Watson & Dallwitz (1994): genus not recognised. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae. 3 species (W. proluta, W. pungens, W. subxerophylla).

Distribution, phytogeography, ecology. Eastern Australia.

Shade species (?).

References, etc. Morphological/taxonomic: Wills, K.E. and Bruhl, J.J. (2000). Aust. Syst. Bot. 13, 437–468.

Special comments. Fruit data wanting. Anatomical data for ts only and wanting.

Illustrations. • Walwhalleya proluta, as Panicum prolutum: Turner, Austr. Grasses (1895).

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: 15th June 2025. delta-intkey.com’.

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