Centrolepidaceae Flora 5

Small monoecious annual or perennial herbs; roots fine, numerous; rhizomes absent; stems very short, branching at ground level to form leafy tufts; leaves near-basal, numerous, with open scarious-hyaline sheaths passing into narrowly linear laminae, 1-veined; hairs eglandular, multicellular uniseriate, or absent. Inflorescence a terminal spike or capitulum, usually scapose, several per plant; flowers unisexual, minute, wind-pollinated, enclosed by herbaceous primary bracts; small hyaline secondary bracts often also present; perianth and floral receptacle absent; male flower reduced to a single stamen; female flower reduced to an apocarpous gynoecium of 1–30 carpels; male and female flowers sometimes associated to form asymmetric bisexual units with a stamen adaxial to the carpels; filament capillary; anther elliptic, dorsifixed, versatile, 1-celled; ovary stipitate, utricular with pericarp remaining hyaline in fruit, 1-celled; ovule 1, pendulous, orthotropous; styles filiform, entire, papillose and stigmatic along most of their exposed length. Fruit dry, 1-seeded, membranous, dehiscent; seed endospermic, with a minute apical embryo; testa membranous.

3 genera with about 37 species, mainly Australian, also in SE Asia, New Zealand, New Guinea, S America and the Falkland Islands. 10 species in S.A.

The family is a homogenous group whose exact relationship to other Poales is still questionable.

Small annuals; leaves filiform to subulate in a basal tuft; scapes erect, filiform, leafless. Inflorescence a laterally flattened terminal spike resembling the spikelets of Cyperus spp.; rhachis flexuose; primary bracts 6–18, distichous, imbricate, glume-like, herbaceous with hyaline margins; lowest 1 or 2 primary bracts each enclosing 1–3 stamens and sometimes 1 separate carpel; each stamen subtended by a short ovate hyaline secondary bract; upper primary bracts shorter, each enclosing 1 solitary carpel; ovary narrowly ovoid; style brownish, exserted from bracts. Seed fusiform, smooth.

Annual 2–4 cm high; leaves filiform, lax, acute, 1–2.5 cm long, glabrous. Scapes 1.5–3.5 cm long, glabrous; spike ovate, 3–4 mm × 2–3 mm, turned to one side; lowermost bract erect, 3–4 mm long, acuminate, contracted into a linear tip 1–2 mm long, glabrous to papillose, enclosing 1 or 2 stamens often also with 1 carpel; upper bracts 5–7, obtuse, 0.8–1.5 mm long, pilose, rounded on the dorsal surface, 3-veined, with broad ciliolate hyaline margins extending to the apex, at first closely imbricate, eventually separating due to growth of the rhachis and ultimately deciduous; carpels solitary, lacking secondary bracts. Seed pale-brown, 0.7 mm long. Slender aphelia.

Annual 1–3 cm high; leaves subulate to linear, acute, 1–2 cm long, glabrous. Scapes 0.7–2.5 cm long; spike ovate, 4–6 mm × 3–4 mm, erect; lowermost bract leaflike, 4–10 mm long, spreading, glabrous, enclosing 1–3 stamens; the next bract 3–6 mm long, with a spreading leaf-like tip, glabrous, enclosing 1–3 stamens; upper bracts 4–9, acuminate, 1.5–2.5 mm long, keeled, with hairs along the keel, with broad hyaline ciliate margins not extending to the apex, remaining closely imbricate, deciduous in fruit; carpels each with an ovate ciliolate secondary bract on the abaxial side. Seed dark-brown, 0.8 mm long. Dwarf aphelia.

Small annual and perennial herbs; leaves linear, forming a basal tuft; innermost leaf often reduced to a short sheath. Scapes erect, leafless or absent; inflorescence a head of 1–numerous sessile reproductive units enclosed by a pair of herbaceous primary bracts with dilated sheathing bases appearing opposite, often produced beyond the head as leaf-like laminae; each female flower usually associated with a solitary stamen free or partially adnate at the base to form a bisexual unit; gynoecium of 2–30 carpels superposed in 2 rows (often alternating) along a vertical axis formed from the stipes of the carpels; secondary bracts hyaline, 2 or 3 surrounding each bisexual unit, or absent; ovaries ovoid, more or less connate; styles filiform, connate at least at the level of the ovaries, forming a brush-like bundle exserted from the bracts. Seed ovoid, smooth, pale-brown, translucent.

C. cephaloformis (2)

1. Heads sessile among the basal leaves

1: Heads scapose

2. Leaves pilose, at least near the base

C. fascicularis (5)

3. Perennial; gynoecium with 2–4 carpels

3: Annuals; gynoecium with 4–7 carpels

C. drummondiana (3)

4. Bracts glabrous

C. strigosa (8)

4: Bracts hairy

2: Leaves completely glabrous

C. aristata (1)

5. Leaves manifestly distichous; both bracts of the head with long leaf-like laminae

5: Leaves not appearing distichous; outer bract only with a leaf-like lamina

C. glabra (6)

6. Bract lamina straight, no longer than the head; plant softly herbaceous

6: Bract lamina recurved, longer than the head; leaves wiry; bract bases hardened

C. eremica (4)

7. Stamens and gynoecia 4–10 per head

C. polygyna (7)

7: Stamens and gynoecia 1 or 2 per head

Annual herb 2–10 cm high, rigidly erect, bright-green or becoming reddish after flowering; leaves equitant, distichous, linear-subulate, keeled, acute, 1–6 cm × 0.8–1.6 mm, glabrous, shiny; innermost leaf not reduced. Scapes flattened, 2-edged, 1–8 cm long, glabrous; head flattened, oblong-ovoid, 1.3–3 mm wide; primary bracts appearing opposite, with cartilaginous brown bases gaping apart at the apex and leaf-like laminae, glabrous or scabridulous on keel, the outer bract 8–35 mm long, the inner one 4–30 mm; gynoecia 20–30, each with a stamen at its side but not adnate; secondary bracts truncate, 2 or 3 per gynoecium; carpels 3–6; styles connate for about a third of their length above the top ovary. Seed narrowly ovoid, c. 0.7 mm long. Pointed centrolepis.

Minute annual herb forming round moss-like or burr-like tufts 0.4–2 cm diam., pale-green; leaves crowded, subulate, acute, mucronate, 3–8 × 0.5–0.8 mm, recurved, glabrous. Scapes absent; heads sessile, terete, ovoid-conic, 2–3 × 1–1.6 mm; primary bracts appearing opposite, with keeled scarious straw-coloured bases remaining closely sheathing, the outer bract with a recurved subulate lamina 2–4 mm long, the inner one acute without a lamina; gynoecia 1–3; secondary bracts absent; carpels 4–10; styles connate up to half their length above the top ovary. Seed c. 0.5 mm long.

Known in this State only from the type collections on Pearson Island, and Kangaroo Island; two disjunct populations from coastal W.A. are referred to the same subspecies, which may be a relic widely supplanted on the mainland by the more specialised subsp. cephaloformis.

Annual herb forming grass-like tufts to 6 cm diam., pale-green; leaves numerous, linear, acute, 1–3 cm × 0.7–1 mm, lax, sparsely pilose near the base, glabrous to papillose above; innermost leaf reduced to an obtuse hyaline sheath. Scapes few, terete, filiform, 3–5 cm long, glabrous; head terete, ovoid-conic, 3–4 mm × c. 1.5 mm; primary bracts separated by a minute internode, closely sheathing, subequal, acute, minutely mucronate or with capillary points to 2 mm long, glabrous; gynoecia 4–10; secondary bracts acute, 2 per gynoecium; carpels 4–7; styles connate for about half their length above the top ovary. Seed c. 0.5 mm long.

Annual herb 2–4.5 cm high, forming hemispherical tufts 1.5–6 cm diam., dull-green; leaves numerous, crowded, linear to subulate, obtuse, terete, 4–15 × 0.5–0.7 mm, wiry, recurved, glabrous; innermost leaf reduced to an obtuse scarious-hyaline sheath. Scapes numerous, terete, wiry, 1.5–3 cm long, glabrous; head terete, ovoid-conic, 2–3.5 × 1–2 mm; primary bracts appearing opposite, with brown cartilaginous bases remaining closely sheathing, the outer bract with a recurved subulate lamina 2–8 mm long, the inner one acute without a lamina; gynoecia 4–10, each with a stamen at its side but not adnate or some lacking the stamen; secondary bracts absent; carpels 7–20; styles shortly connate above the top ovary. Seed c. 0.6 mm long.

Perennial herb forming dense cushions 3–12 cm diam., bright-green; leaves numerous, linear-filiform, acute, 1–4.5 cm × c. 0.8 mm, straight, spreading, soft, sparsely pilose in the basal half; innermost leaf reduced to a hyaline sheath. Scapes few, terete, filiform, 2.5–6 cm long, glabrous; head broadly ovoid, c. 3 mm long; primary bracts separated by a minute internode, gaping apart, subequal, with keelless herbaceous stiffly hairy bases tapered into glabrous leaf-like apices to 3 mm long; gynoecia 8–14 each with a stamen at its side but not adnate; secondary bracts mostly truncate, 2 per gynoecium; carpels 2–4; styles connate only to the top ovary. Seed c. 0.5 mm long; scapes and bracts persistent after fruiting. Tufted centrolepis.

Annual or ephemeral herb 1–4, exceptionally to 8 cm high, softly herbaceous, forming small scattered tufts, dull-green or becoming reddish; leaves few, linear to filiform, acute, 1–8 cm × 0.5–1 mm, lax, flattened, glabrous,; innermost leaf reduced to an obtuse hyaline sheath. Scapes few, terete, filiform, 1–7 cm long, glabrous; head cylindrical, 2–3 mm × c. 0.7 mm; primary bracts appearing opposite, gaping apart at apex, glabrous, herbaceous with hyaline margins, the outer bract with a capillary green lamina 0.8–3 mm long, the inner one acute without a lamina; gynoecia 4–6; secondary bracts absent; carpels 5–7; styles connate only to the top ovary, red. Seed c. 0.5 mm long. Smooth centrolepis.

Annual herb 1.5–6 cm high, forming small scattered tufts, dull-green becoming red-brown after flowering; leaves crowded, linear-subulate, acute or mucronate, terete, 4–12 × 0.5–0.8 mm, wiry, recurved, glabrous; innermost leaf reduced to an obtuse scarious-hyaline sheath. Scapes terete, filiform, 1–5 cm long, glabrous; head terete, cylindrical, 3–5 × c. 1 mm; primary bracts appearing opposite, with dark-brown cartilaginous bases remaining almost closed, the outer bract with a recurved subulate lamina 3–10 mm long, the inner one acute without a lamina; gynoecia 1 or 2, each with a stamen shortly adnate the gynoecium axis; secondary bracts absent, or rarely 1, minute, scarious; carpels 6–26; styles shortly connate above the top ovary. Seed c. 0.5 mm long. Wiry centrolepis.

Annual herb 2–7 cm high, bright-green; leaves numerous, crowded evenly to form a neat hemispherical tuft, linear-subulate, acute, mucronate, 1–2.5 cm × c. 0.8 mm, straight, spreading, soft, pilose; innermost leaf reduced to a hyaline sheath. Scapes terete, filiform, 1.5–6 cm long, glabrous or minutely pubescent; head ovoid, 3–4 mm long; primary bracts separated by a minute internode, gaping apart, subequal, with keelless herbaceous stiffly hairy bases contracted into terete glabrous points to 1 mm long; gynoecia 10–20, each with a stamen at its side but not adnate; secondary bracts truncate, 2 or 3 per gynoecium; carpels 5–7; styles shortly connate above the top ovary. Seed c. 0.5 mm long. Hairy centrolepis.

Ilustration by G.R.M. Dashorst, from Flora of South Australia 4: 1827, Fig. 835 (1986).
*Centroplepis eremica*: A, habit; B, leaf apex; C, pseudanthium; D, flower head, lateral and ventral view.
*Centrolepis polygona*: E, habit; F, leaf apex; G, pseudanthium; H, flower head, lateral and ventral view.

Illustration by G.R.M. Dashorst, from Flora of South Australia 4: 1824, Fig. 833 (1986).
*Aphelia gracilis*: A, habit; B, spike.
*Aphelia pumilo*: C, habit; D, spike.

Ilustration by G.R.M. Dashorst, from Flora of South Australia 4: 1825, Fig. 834A (1986).
*Centroplepis aristata*: A, habit; B, pseudanthium.

Ilustration by G.R.M. Dashorst, from Flora of South Australia 4: 1828, Fig. 836B (1986).
*Centrolepis glabra*: A, habit; B, pseudanthium.