| # The grass genera of the world |

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

### Symplectrodia Lazarides

From the Greek sym- (together or united), plekton (a spur) and odous (tooth), contrasting an entire basal lemma with 3-toothed or 3-lobed lemmas in the related genus Triodia.

Type species: Type: S. lanosa Lazarides.

Habit, vegetative morphology. Perennial (robust or slender); caespitose (and rhizomatous). Culms 30–135 cm high. Culm nodes hairy, or glabrous. Culm internodes solid. Plants conspicuously armed. The shoots not aromatic. Leaves not basally aggregated; non-auriculate; with hair tufts in the ligule region. Sheath margins free. The basal sheaths sometimes reddish brown or with woolly hairs. Leaf blades narrow; acicular; hard, woody, needle-like (cf. Triodia); without abaxial multicellular glands; not pseudopetiolate; without cross venation. Ligule a fringe of hairs. Contra-ligule absent.

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

Inflorescence. Inflorescence paniculate; open to contracted. Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; long pedicellate.

Female-fertile spikelets. Spikelets not noticeably compressed; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets (the internode above the fertile floret up to 5 mm long and adnate to the palea, and the upper internodes also elongated at maturity, with the sterile florets ultimately disarticulating individually). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus present. Callus pointed (curved or oblique).

Glumes two; very unequal; shorter than the spikelets to about equalling the spikelets; long relative to the adjacent lemmas; hairless; usually glabrous; pointed; awned to awnless (often aristulate); non-carinate (rounded or flattened dorsally); similar (cartilaginous, lanceolate-elliptic, acuminate). Lower glume 1–5 nerved. Upper glume 3–7 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets (without paleas, often reduced). The distal incomplete florets 2–5; clearly specialised and modified in form (empty, cartilaginous, 3-lobed, 3-nerved, unequally 3-awned, finally becoming distant and prominently exserted by elongation of the internodes); awned.

Female-fertile florets 1. Lemmas similar in texture to the glumes (cartilaginous); entire; pointed; awned. Awns 1; median; apical; non-geniculate; hairless; much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas hairy (marginally and on the midnerve), or hairless; without a germination flap; 3 nerved. Palea present; relatively long; entire (acute); awnless, without apical setae; hardened and adnate to the rachilla below; 2-nerved; 2-keeled. Lodicules present; 2; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small to medium sized (4–4.5 mm long); ellipsoid; longitudinally grooved (on the hilar face); compressed dorsiventrally. Hilum short. Pericarp fused. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (the intercostal zones sunken in narrow grooves, inaccessible for observation in surface view). Papillae present; intercostal, or costal and intercostal. Intercostal papillae not over-arching the stomata; consisting of one oblique swelling per cell, or consisting of one symmetrical projection per cell, or several per cell. Microhairs present; elongated; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs about 39 microns long (where recordable); 15 microns wide at the septum. Microhair total length/width at septum 2.6. Microhair apical cells 7.5 microns long. Microhair apical cell/total length ratio 0.19. Stomata not observable; 18–21 microns long. Subsidiaries papillate, or non-papillate. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; ‘panicoid-type’; dumb-bell shaped (large and sometimes very asymmetric); not sharp-pointed.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section infolded permanently; circular. The adaxial channel parallel-sided, with a digitate base.

C4. The anatomical organization unconventional. Organization of PCR tissue Triodia type (PCR ‘sheaths’ lateral only or ‘draping’). XyMS+. PCR sheath outlines even, or uneven to even. Mesophyll traversed by columns of colourless mesophyll cells (linking the adaxial and abaxial grooves); with arm cells (cf. Sclerodactylon, Triodia). Leaf blade ‘nodular’ in section; with the ribs very irregular in sizes. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (incorporated in or linked with the colourless girders). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (large anchors). Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in a continuous abaxial layer.

Classification. Watson & Dallwitz (1994): Chloridoideae; Triodieae. Soreng et al. (2015): Chloridoideae; Cynodonteae; Triodiinae. 2 species.

Distribution, phytogeography, ecology. Australia.

Xerophytic; species of open habitats.

References, etc. Morphological/taxonomic: Lazarides 1985. Leaf anatomical: studied by us - iS. lanosa M. Lazarides, S. gracilis M. Lazarides.

Illustrations. • Symplectrodia lanosa spikelet with glumes removed: this project. • Callus of S. lanosa. • Symplectronia lanosa, abaxial epidermis of leaf blade: this project. • Symplectrodia lanosa, TS leaf blade: this project.

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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