Rytidosperma Steud.

Volume V (2000) - Flora of New Zealand Gramineae

Rytidosperma Steud., 1854

=Notodanthonia Zotov, N.Z. J. Bot. 1: 104 (1963)

≡Thonandia H.P.Linder, Telopea 6: 612 (1996) nom. illeg.

Type species: R. lechleri Steud.

Tufted perennials, short or moderately tall, with intra- or extravaginal branching. Leaf-sheath with apical tuft of hairs sometimes extending dorsally, abaxially ± shining, glabrous or hairy. Ligule a rim of hairs. Leaf-blade persistent or disarticulating at ligule, flat or inrolled, ± flaccid, or stiff, abaxially glabrous or hairy, adaxially minutely prickle-toothed, occasionally with long hairs, margins smooth or scabrid. Inflorescence a raceme, racemose panicle or panicle. Rachis and pedicels slender, often hairy at branch-axils and usually scabrid to hairy below erect few- to several-flowered spikelets; florets ⚥; disarticulating above glumes and between florets. Glumes ± equal, firmly membranous, keeled above, nerves 3-13, anastomosing, occasionally internerves long-hairy, adaxially with minute prickle-teeth. Lemma with two scabrid lateral lobes usually tipped by a minute to long, straight awn; central awn from sinus longer and stronger, usually geniculate, column ± twisted; nerves 5-9, anastomosing; abaxially pilose in two complete or incomplete transverse series of tufts of rigid hairs, sometimes reduced to marginal tufts. Palea membranous, keels and apex finely ciliate, interkeel glabrous or hairy, margins glabrous or with a few long hairs below. Callus abaxially ± flat or rounded, disarticulation oblique, margins variously long hairy. Rachilla and prolongation glabrous. Lodicules 2, cuneate, apically long-hairy, or glabrous. Stamens 3. Gynoecium: ovary glabrous; styles 2, free, swollen below. Caryopsis free, obovate to elliptic, planoconvex; embryo ⅓-½ caryopsis; hilum ± ⅓-⅕ caryopsis, round to somewhat elliptic. Chasmogamous and cleistogamous. Plates 6A, 11, 12.

SYNOPSIS

A.
- Tufts often low-growing, branching mainly intravaginal. Leaf-blades ± inrolled, disarticulating at ligule; lemma lobes, including fine, short or minute awn, o, sometimes > lemma, adaxially glabrous, rarely slightly scabrid; palea narrow-spathulate to elliptic; 10 spp. endemic, 2 indigenous shared with Australia:
- 2. australe, 4. buchananii, 7. corinum, 12. maculatum, 15. nudum, 17. petrosum, 19. pulchrum, 20. pumilum, 22. setifolium, 23. tenue, 25. thomsonii, 27. viride
B.
- Tufts stiff, often hoary, branching mainly intravaginal. Leaf-blades ± flat, persistent; lemma lobes, including conspicuous awn, 2× lemma, adaxially scabrid; palea broad-ovate or elliptic; mostly naturalised Australian spp.:
- 1. auriculatum, 3. biannulare, 5. caespitosum, 8. erianthum, 9. geniculatum, 11. laeve, 18. pilosum, 24. tenuius
C.
- Tufts ± lax, leafy, often large, branching mainly extravaginal. Leaf-blades ± flat, persistent; lemma lobes, including conspicuous awn, 2× lemma, adaxially scabrid or glabrous; palea narrow-elliptic; native and naturalised spp.:
- 6. clavatum, 10. gracile, 13. merum, 14. nigricans, 16. penicillatum, 21. racemosum, 26. unarede

Key

Lateral lemma lobes exceeding upper lemma hairs and at least twice as long as lemma

Lateral lemma lobes concealed by upper lemma hairs, or visible above them and at most only slightly longer than lemma

Upper lemma hairs in a few isolated tufts, short, at most hardly exceeding lemma

Upper lemma hairs in a continuous dense or sparse row, long, much exceeding lemma

Callus hairs short, rarely reaching lower row of lemma hairs; or lower row in marginal tufts only

Callus hairs overlapping lower row of lemma hairs

Lemma hairs in continuous lower row and in an interrupted, tufted upper row; callus long, narrow, up to 1.5 mm

21. racemosum

Lemma hairs in two pairs of marginal tufts only, occasionally a few single hairs in lower row; callus short, stout, up to 1 mm

13. merum

Branching intravaginal; palea usually just reaching awn sinus

18. pilosum

Branching extravaginal; palea usually exceeding awn sinus

Culm scabrid just below contracted panicle or quite glabrous; awn column usually flat at base of sinus and concealing top of palea

6. clavatum

Culm minutely hairy to scabrid for 10 mm or more below elongated panicle; awn column twisted and divergent at base of sinus and revealing top of palea

16. penicillatum

Upper lemma hairs exceeding or equalling awn column

Upper lemma hairs shorter than awn column

Lower row of lemma hairs short, or just reaching upper row

Lower row of lemma hairs distinctly overlapping upper row, or lower row in marginal tufts only

Lemma with only a few scattered hairs between two rows of hairs; awn column equalling or just exceeding palea-tip; branching extravaginal

26. unarede

Lemma with numerous scattered hairs between two rows of hairs; awn column much exceeding palea-tip; branching intravaginal

3. biannulare

Lower row of lemma hairs in marginal tufts only; palea interkeel glabrous

11. laeve

Lower row of lemma hairs continuous; palea interkeel long-hairy

Lateral lemma lobes entire at base; callus (0.8)-1-1.3 mm

24. tenuius

Lateral lemma lobes shallowly lobed again at base; callus 0.4-0.7 mm

1. auriculatum

Upper row of lemma hairs sparse to almost continuous, equalling or not reaching tip of palea

Upper row of lemma hairs continuous, exceeding tip of palea

Rachis and pedicels closely short-scabrid, with hairs at branch axils only slightly longer; upper lemma hairs ± continuous

7. corinum

Rachis and pedicels almost glabrous, and usually with small tufts of long hairs at axils; upper lemma hairs very sparse

17. petrosum

Palea narrow-lanceolate, much exceeding awn sinus; lower lemma hairs almost reaching upper

5. caespitosum

Palea broadly obovate, ± equalling awn sinus; lower lemma hairs short, and lemma body shining between two rows

8. erianthum

Upper lemma hairs very much exceeding tip of palea

Upper lemma hairs ± equalling or shorter than tip of palea

Callus hairs short, sparse, not reaching to lower row of lemma hairs or scarcely overlapping them; branching extravaginal

Callus hairs long, abundant, greatly overlapping lower row of lemma hairs; branching intravaginal

Lemma short-hairy between two rows of hairs; awn column overtopped by or equalling tip of palea

10. gracile

Lemma ± glabrous between two rows of hairs; awn column exceeding or equalling tip of palea

14. nigricans

Upper and lower lemma hair rows equally dense and continuous; glumes linear-lanceolate, gradually narrowed to tip, overtopped by awns

27. viride

Upper row of lemma hairs continuous, lower less dense, sometimes ill-defined; glumes broad at base, shortly narrowed to tip, equalling or overtopping awns

9. geniculatum

Panicle branches glabrous, or with few scattered teeth and occasional long hairs at branch axils; anthers (1.2)-1.5-3 mm

22. setifolium

Panicle branches ± closely short-scabrid, usually with some slightly longer hairs below spikelets and occasionally at branch axils; anthers 0.2-1-(1.4) mm

Lemma hairs sparse in both rows, or in marginal tufts only, sometimes with a few scattered hairs at centre, or glabrous

Lemma hairs in dense continuous rows, or dense in upper row only

Lateral lemma lobes well developed, > 1 mm; awn usually divergent; palea ± reaching top of awn column

4. buchananii

Lateral lemma lobes minute, up to 0.5 mm; awn erect, or reduced to a mucro; palea at most reaching base of awn

Lemma glabrous apart from upper and lower pairs of marginal tufts

25. thomsonii

Lemma with sparse hairs between marginal tufts or with scattered hairs in upper half, or with a single pair of marginal tufts, or lemma entirely glabrous

Lemma with awn 1-2 mm

15. nudum

Lemma mucronate

Lemma glabrous, or rarely with a single pair of marginal tufts; leaf-blades flat to folded

2. australe

Lemma ± hairy; leaf-blades setaceous

20. pumilum

Upper row of lemma hairs noticeably shorter than lemma lobes; pedicels with dense long stiff hairs below spikelet

12. maculatum

Upper row of lemma hairs ± equalling or exceeding lemma lobes; pedicels uniformly short-scabrid, occasionally long hairs below spikelet

Lemma glabrous between rows of hairs; callus hairs overlapping lower marginal hair tufts

19. pulchrum

Lemma with scattered hairs between rows of hairs; callus hairs not, or a few just reaching lower marginal hair tufts

23. tenue

c. 45 spp. from South America, New Guinea and Australasia. Endemic spp. 15, indigenous spp. 3, shared with Australia; naturalised spp. 9 (all from Australia).

Connor, H. E. and Edgar, E. N.Z. J. Bot. 17: 311-337 (1979), presented a full treatment of Rytidosperma Steud. in place of the synoptic arrangement by Zotov, V. D. N.Z. J. Bot. 1: 78-136 (1963) as Notodanthonia. Rytidosperma, as indicated by Nicora, E. Darwiniana 18: 80-106 (1973), is the earliest correct name for taxa that Zotov (loc. cit.) included in Notodanthonia Zotov, which earlier were known here as Danthonia DC. [Cheeseman, T. F. Man. N.Z. Fl. 171-179 (1925)]. See also Vickery, J. W. Contrib. N.S.W. Natl Herb. 2: 249-325 (1956); Baeza P., C. M. Sendtnera 3: 11-93 (1996); and Astegiano, M. E., Anton, A. M. and Connor, H. E. Flora Fanerogámica Argentina 22: 15-19 (1996). Connor, H. E. and Edgar, E. N.Z. J. Bot. 25: 115-170 (1987), included spp. of Erythranthera Zotov within Rytidosperma as was indicated by Clayton and Renvoize (1986 op. cit. p. 175).

Linder, H. P. Telopea 7: 269 (1997) proposed Austrodanthonia as a new genus to accommodate those species of Zotov's Notodanthonia sect. Semiannularia and sect. Notodanthonia subsect. Clavatae, retaining Notodanthonia sens. strict. for Zotov's section Notodanthonia ≡Thonandia H.P.Linder nom. illeg. The original proposals of Linder, H. P. and Verboom, G. A. Telopea 6: 591-626 (1996) are thereby made nomenclaturally correct. As they affect New Zealand that arrangement seems confusing compared with our earlier synoptic subdivisions of Rytidosperma which ally themselves logically with Zotov's infrageneric treatment; none of his sections and subsections has been formally transferred from Notodanthonia.

These informal groups, A, B, and C, correspond with sections formally described by Zotov (1963 op. cit.) as Notodanthonia sect. Buchanania, sect. Semiannularia, and sect. Notodanthonia respectively, though R. pilosum may be more appropriately placed in group C. The spp. referred by Zotov (1963 op. cit.) to Erythranthera are placed in group A.

The common name, danthonia, is applied to all spp. of Rytidosperma in N.Z.

Rytidosperma Steud.

SYNOPSIS

Key

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