Poa xenica Edgar & Connor
; Holotype: CHR 514884a! G. Jane Riwaka River, bluffs in South Branch, 600 m, 3 Dec 1997; ♂.
Coarse long-leaved, dioecious, extravaginally branching often pendulous grass with elongate internodes and rooting at nodes; leaf-blades persistent. Leaf-sheath 10 cm, keeled, ribbed, open to base, becoming dull brown and fragile, finely retrorsely hairy, margin membranous, darker brown. Ligule 1 mm, ciliate, abaxially finely hairy. Collar conspicuous, margin short hairy. Leaf-blade to 80 cm × 3-4 mm, coriaceous, folded below and at apex, ± flat elsewhere, abaxially glabrous with some long hairs near collar, adaxially clothed with many small antrorse hairs, denser near ligule; margins very sparsely prickle-toothed below becoming almost smooth but apex prickle-toothed and sharp-pointed. Culm to 85 cm, many noded, erect or with some geniculate nodes, nodes swollen, coloured, glabrous; internodes glabrous. Panicle to 25 cm, open, violet-suffused, subtended by bract to 2.5 mm; several to many solitary rarely binate branches at internodes, naked below with solitary spikelets, branches > internodes; rachis glabrous, branches and pedicels glabrous to sparsely shortly prickle-toothed. Spikelets 10-12 mm × 2 mm, gaping at anthesis, (1)-3-4-6 widely separated florets. Glumes unequal, centrally green, violet elsewhere, nerves elevated; lower 2.5-3.5 mm, 1-3-nerved, upper 3.5-5 mm, 5-nerved (3 long, 2 short) adaxially shortly hairy at apex, margins ciliate. Lemma 4.5-6 mm, 5-nerved, centrally green, violet elsewhere, abundantly finely pubescent throughout, keel prickle-toothed above, margins ciliate, membranous above, apex recurved, shortly lobed and mucronate (0.05 mm or 0) becoming erose. Palea 4.5-5.2 mm, ≤ lemma, apex bifid, keels minutely stiff hairy. Callus 0.25 mm, short, blunt, glabrous or with a few prickle-teeth. Rachilla 1.5 mm, glabrous or with a few prickle-teeth at base; prolonged. Lodicules 0.5-1.0 mm, acutely lobed, tip ciliate. Anthers (a) male flowers: 2.75-3-3.75 mm, yellow or violet-suffused; (b) female flowers: 2-2.2 mm, white, pollenless. Gynoecium (a) male flowers: 0.8-1.0 mm; (b) female flowers: ovary 0.8-1.2 mm, glabrous; stigma-styles 2-3-3.5 mm, widely disposed, stigmatic hairs almost to base. Caryopsis not seen.
S.: Nelson (South Branch Riwaka River). Scree at foot of steep marble bluffs and in shrublands; known only from this area; 500-700 m.
Endemic.
HYBRIDS
Nine hybrid combinations between indigenous spp. of Poa were recorded by Edgar (1986 op. cit. pp. 487-495) : P. astonii × P. foliosa, Stewart Id region (≡P. ×poppelwellii Petrie, T.N.Z.I. 46: 38 (1914); Holotype: WELT 66222! D. Petrie ex D. L. Poppelwell grown on [from] a live plant from Herekopere Islet, early Dec. 1912); P. astonii × P. tennantiana, Stewart Id region, 2 n = 42; P. aucklandica subsp. campbellensis × P. foliosa, Campbell Id (≡P. novae-zelandiae var. desiliens Zotov, Rec. Dom. Mus. 5 (15): 127 (1965); Holotype: CHR 119433! V. D. Zotov Campbell Is., Mt Lyall, 6.1.1961); P. breviglumis × P. colensoi, Ruahine Mts, Mt Stokes, Garvie Mts; P. colensoi × P. novae-zelandiae, Tararua Ra., South Id mountains; P. hesperia × P. subvestita, Fiordland; P. imbecilla × P. lindsayi, Canterbury, North Otago; P. lindsayi × P. novae-zelandiae, Mt Cook; P. maniototo × P. pygmaea, Pisa Ra.
All are sterile; the anthers were either pollenless, or pollen-sterile, or only slightly pollen-fertile, the stigmas were usually imperfect and no caryopses were seen.
Edgar (1986 op. cit. p. 493) cited the distribution of P. hesperia × P. subvestita as Fiordland and western Otago; specimens from western Otago are now referred to P. schistacea.
Two further putative hybrids are reported here:
Small dense tufts, 3-4 cm, with short, stiff, rolled leaves; some leaf-blades disarticulating. Panicle 1-1.5 cm, of 3-4 spikelets. Lemma with very short fine hairs on lower ½. Anthers 1.2-1.3 mm, pollen-sterile. Gynoecium with well-developed stigmas.
Only two specimens seen: CHR 395475 A. P. Druce Mt Pisa, 6300 ft, herbfield, 1988; CHR 394597 A. P. Druce Mt Pisa, 6400 ft, rocky ground, 1989.
Rhizomatous tufts 20-40 cm, with narrow, folded, rather stiff leaves. Ligule 1-4 mm. Panicles erect, ± pyramidal, 4-6 cm; branches glabrous. Spikelets 5-6 mm, 3-4-flowered, purplish. Lemma 5-nerved, glabrous apart from short hairs on lower ⅓ of keel and near base of outer lateral nerves. Callus with tuft of crinkled hairs. Anthers 0.5-0.7 mm, pollen-sterile. Gynoecium 1-2 mm. Upper florets sometimes with anthers c. 0.3 mm and gynoecium 0.5 mm.
Specimens seen: CHR 394596, CHR 395184 A.P. Druce Pisa Range, wet seepages, 1989, and CHR 395204 A.P. Druce Harris Mts, wet seepage, 1989.
A sterile Poa, c. 70 cm, CHR 223383 G. C. Kelly hanging down almost vertical cliffs at Dan Rogers Creek, Akaroa Harbour, 1971, may be a hybrid, P. anceps × P. astonii, or P. anceps × P. colensoi; branching extravaginal; leaf-blades narrow, inrolled; panicle 6 cm, shortly branched; spikelets c. 7 mm; glumes and lemmas acute to acuminate and glabrous, callus with copious long crinkled hairs; anthers 1.5-2.5 mm, somewhat pollen-fertile; gynoecium 0.1 mm, without stigmas.
REPRODUCTIVE BIOLOGY
Anton, A. M. and Connor, H. E. Aust. J. Bot. 43: 577-599 (1995) is a comprehensive survey of floral biology and reproduction in the genus. The majority of N.Z. spp. of Poa are ⚥, but a few dioecious spp., without floret dimorphism, and some gynomonoecious spp. are also present. Dioecious spp. are: P. foliosa, P. schistacea, P. subvestita, P. sudicola, and P. xenica. Gynomonoecious spp. are: P. cookii, P. novae-zelandiae, P. ramosissima, and naturalised P. annua.
Five collections of P. foliosa from the Stewart Id area were ⚥ rather than dioecious. Anthers in ⚥ plants were 2-2.5 mm, stigma-styles c. 1.5 mm, and seed was set. There seemed to be no vegetative or inflorescence differences between ⚥, ♂ or ♀ specimens.
For dioecious P. sudicola there is only one collection of ♂ plants (CHR 369893 from Pike Peak). Collections from Matiri Range and Turks Cap Range are ♀ plants with developing but immature caryopses.
Connor, H. E. N.Z. J. Sci. Tech. 38A: 742-751 (1957), demonstrated that P. colensoi was self-incompatible, P. cita (as P. caespitosa) inefficiently self-compatible, and P. breviglumis in all probability self-compatible.
All spp. in N.Z. flower chasmogamously. Species with short anthers, P. breviglumis, P. buchananii, P. imbecilla, P. incrassata, P. lindsayi, P. maniototo, P. matthewsii, P. senex, P. tonsa, have tendencies to cleistogamy and all seem very self-fertile.
Ovaries, and these resemble caryopses, are infected by the smut fungus Tilletia cathcartae, also known in New Zealand on three specimens of Poa pusilla (E. H. C. McKenzie in Edgar and Connor 1999 op. cit. p. 67).
G. Jane (in litt.) remarks that this species is known only from four particular sites on very steep marble bluffs and the scree below. A preference for damp shaded sites is detected. The populations are quite large, inaccessible, and not imminently endangered.
CYTOLOGY
Chromosome counts for indigenous spp. were reported by Hair, J. B. N.Z. J. Bot. 6: 267-276 (1968). Most are tetraploid, 2 n = 28, but species are also 6 x, 8 x, 12 x, 16 x and c. 38 x. Connor, H. E. and Edgar, E. in Barlow, B. A. (Ed.) 1986 (Flora and Fauna Alpine Australasia 413-434) reported two evident polyploid series within related spp., one within the wide-leaved tussock spp. of southern and subantarctic islands, i.e., P. foliosa, 4 x (2 n = 28), and P. tennantiana, 8 x (2 n = 56), the second series occurring in the folded- or narrower-leaved tussock spp., i.e., P. anceps, 4 x (2 n = 28), P. cita, 12 x (2 n = 84), P. cockayneana and P. chathamica, 16 x (2 n = 112) and finally P. litorosa, c. 38 x (2 n =c. 266). So far as is known, the count for P. litorosa is the highest chromosome number yet recorded in Gramineae or in the Monocotyledons as a whole [Hair, J. B. and Beuzenberg, E. J. Nature 189: 160 (1961)].
The chromosome count, 2 n = 28, recorded for P. exigua by Hair, J. B. (1968 op. cit.) was based on a plant collected from Mt Potts, S. Canterbury, CHR 102397. The specimen has not been traced, and, as Mt Potts is outside the known range of P. incrassata (=P. exigua) the chromosome count must be regarded as doubtful. A count of 2 n = 29, recorded for P. foliosa on Macquarie Id by Moore, D. M. Bot. Not. 113: 187 (1960) is also regarded as doubtful.
UNASSIGNED OR EXCLUDED NAMES
Poa laevis var. α brevifolia Hook.f., Fl. N.Z. 1: 307 (1853) : no specimens so labelled were found at Kew; the name may refer to P. colensoi.
Poa hypopsila Steud., Syn. Pl. Glum. 1: 263 (1854) : no specimen could be found at P; the original locality cited is N.Z. and no collector is given.
Eragrostis eximia Steud., Syn. Pl. Glum. 1: 279 (1854) : Steudel cited Urville as the original collector, from "N. Holl. N. Zeelandia"; the type specimen at P is a single panicle of Poa, labelled in Steudel's hand "Bromus Urville N. Zeelandia"; glumes and lemmas are longer, narrower, more acute and more prominently nerved than in N.Z. spp. and the name probably refers to an Australian species.
