Poa binata Nees, Fl. Afr. Austral. Ill. 378. 1841.

Soreng, Robert J., Sylvester, Steven P., Sylvester, Mitsy D. P. V. & Clark, Vincent Ralph, 2020, New records and key to Poa (Pooideae, Poaceae) from the Flora of Southern Africa region and notes on taxa including a diclinous breeding system in Poa binata, PhytoKeys 165, pp. 27-50 : 27

Poa binata Nees, Fl. Afr. Austral. Ill. 378. 1841. Fig. 1

= Poa atherstonei Stapf, Fl. Cape. 7: 713. 1900. Type: SOUTH AFRICA. Central Region: Graaff Reinet. Div., summit of Compass Berg, Atherstone 46 (holotype: K (K000345194 [image!]); isotype: PRE fragm. ex K!).

= Poa bidentata Nees, Fl. Afr. Austral. Ill. 3-379. 1841. Type: SOUTH AFRICA. (without precise location), Zeyher s.n. [1832] (holotype: K (K000345195 [image!]); isotype: PRE fragm. ex K!).

= Poa heterogama Hack., Rec. Albany Mus. 1: 112. 1904. Type: SOUTH AFRICA. Kentani, [valleys after grass fire, 1000 ft [305 m], frequent], Aug 1902 [1904 on BM and BOL isotypes; 4 Oct 1904 on GRA isotype; Oct 1904 on K isotypes], Mis Alice Pegler No. 50 (holotype: W (W19160014385 [image!); isotypes: BM (BM000922785 [image!]), BOL (BOL139269 [image!]), GRA (GRA0000194-0 [image!]), K (K000345191 [image!], K000345192 [image!]), PRE (PRE0029722!), US (US00956065 fragm. ex W!)).

Type.

[South Africa. Eastern Cape:] In montibus inter Katrivier et Klipplaatarivier flumina locis graminocis et paludosis alt. 4000-5000' [1219-1525 m], atque in monte Los Tafelberg. alt. 6000' [1829 m], Drège s.n. (lectotype, "9/11 32. [9 Nov 1832] Sumpf auf Gras[ flächen {or} plätzen?].auf dem Katberg, 4000-5000' [1219-1525 m], | af (I af." {original Drège ticket}, {second ticket:} "&. c. 389b | Poa binata N.ab. E. | 27)" (lectotype, designated here: P (P00434748 [image!])).

- sect. unplaced.

Distribution.

Lesotho, South Africa, reaching Zimbabwe. Native, endemic to southern Africa.

Ecology.

cool temperate grasslands.

Flowering.

December to March.

Economics.

common, an important component of high elevation grasslands.

Vouchers.

Lesotho. AfriSki area, in valley adjoining and northwest of the valley of the AfriSki resort, on the north side of the A1 highway, S28.808394 E28.708658, 3104 m alt., basaltic substrate, dry upper slopes above valley, 27 Feb 2020, S.P. Sylvester et al. 3653 (NU, PRE, US); Bokong Nature Reserve, ca. 350 m north from the information centre, S29.067203 E28.421496, 2972 m alt., basaltic substrate, Afro-alpine grassland dominated by Lachnagrostis barbuligera var. barbuligera with moderately-controlled grazing and burning, 2 Mar 2020, S.P. Sylvester et al. 3677 (NU, PRE, US); Bokong Nature Reserve, east of Mafica Lisiu Pass, below the ridge south of the road, S29.066689 E28.40595, 3100 m alt., basaltic substrate, Afro-alpine grassland E, facing burned slope, dominant grass, rich organic topsoil, with many orchids and Senecio macrocephalus , 3 Mar 2020, S.P. Sylvester et al. 3698 (NU, PRE, US); Matebeng Pass, below highest summit close to the pass, S29.868524 E28.976439, 3125 m alt., basaltic substrate, "Lesotho Highland Basalt Grassland" with clear elements of "Drakensberg Afro-alpine Heathland" with Erica and Helichrysum shrubs dominating the landscape, heavy horse grazing, 22 Feb 2020S.P. Sylvester et al. 3582b (NU, PRE, US); Menoaneng Pass, on road between Rafolatsane and Thaba-Tseka, S29.427403 E28.951124, 3039 m alt., basaltic substrate, Afro-alpine grassland, windy ridge, grazed by horses down to low turf, 24 Feb 2020, S.P. Sylvester et al. 3598 (PRE, US); Sani Pass area, ca. 250 m east of Sani Mountain Lodge, S29.584906 E29.291216, 2882 m alt., basaltic substrate, short Afro-alpine grassland, frequently to heavily grazed, soil gravelly loam to 5 cm deep, 25 Feb 2020, S.P. Sylvester et al. 3616 (NU, PRE, US); Sehlabathebe National Park, lower end of the park on the border, S29.860061 E29.095497, 2719 m alt., basaltic substrate, wet Afro-alpine tussock grassland, soil damp, under dripping crag, heavily grazed, close to livestock paths, 19 Feb 2020, S.P. Sylvester et al. 3525 (NU, PRE, US); Sehlabathebe National Park, lower end of the park on the border, S29.877593 E29.086461, 2606 m alt., basaltic substrate, wet Afro-alpine tussock grassland, soil damp, not grazed recently, 20 Feb 2020, S.P. Sylvester et al. 3541 (NU, PRE, US); Tsehlanyane National Park, along path next to 'Black Pool’, S28.900154 E28.452053, 2120 m alt., basaltic substrate, Leucosidea woodland, S facing slope, 4 Mar 2020, S.P. Sylvester et al. 3705 (NU, PRE, US). South Africa. Eastern Cape: Barclay Pass area, Mountain Shadows Hotel, in grassy field behind guest bungalows, S31.203522 E27.838044, 2052 m alt., basaltic substrate, remnant patch of ungrazed native upland grassland, on east facing slope, 14 Feb 2020, S.P. Sylvester et al. 3518 (NU, PRE, US); Eastern Cape: Naudes Nek pass, near Rhodes, S30.764792 E28.105164, 2589 m alt., basaltic substrate, alpine tussock grassland, gently sloping, good soil, 13 Feb 2020, S.P. Sylvester et al. 3489 (US [3 sheets]); Eastern Cape: Tiffindell Ski Area, S30.649239 E27.928720, 2845 m alt., basaltic substrate, alpine grassland, 10 Feb 2020, S.P. Sylvester et al. 3448 (US); Eastern Cape: Tiffindell Ski Area, next to ski lift, S30.651034 E27.925149, 2778 m alt., basaltic substrate, alpine grassland, annually burnt, appears to be seeded with exotic species, 10 Feb 2020, S.P. Sylvester et al. 3453 (NU, PRE, US); Eastern Cape: Tiffindell Ski Area, Ben Macdhui summit, S30.647683 E27.934042, 2995 m alt., basaltic substrate, alpine grassland, 11 Feb 2020, S.P. Sylvester et al. 3458a (NU, PRE, US); Eastern Cape: Tiffindell Ski Area, Ben Macdhui summit, S30.647683 E27.934042, 2995 m alt., basaltic substrate, alpine grassland, 11 Feb 2020, S.P. Sylvester et al. 3458b (US); Eastern Cape: Tiffindell Ski Area, S30.676696 E27.958347, 2522 m alt., basaltic substrate, alpine tussock grassland, 12 Feb 2020, S.P. Sylvester et al. 3481a (NU, PRE, US); Free State: Sentinel trail before reaching the chain ladders that take you up to Amphitheatre, S28.740954 E28.886656, 2857 m alt., basaltic substrate, ungrazed mesic alpine grassland on steep N-facing slope, 5 Feb 2020, S.P. Sylvester et al. 3412 (NU, PRE, US); Kwazulu-Natal: Amphitheatre, slopes near the Tugela waterfall, S28.754008 E28.893853, 2983 m alt., basaltic substrate, alpine grassland, 5 Feb 2020, S.P. Sylvester et al. 3404 (PRE, US); Kwazulu-Natal: Amphitheatre, slopes near the Tugela waterfall, S28.754498 E28.892780, 2979 m alt., basaltic substrate, alpine grassland, 5 Feb 2020, S.P. Sylvester et al. 3407 (US); Kwazulu-Natal: Sani Pass area, below southwest facing cliffs to the southeast of Sani Mountain Lodge, S29.585365 E29.290839, 2866 m alt., basaltic substrate, short Afro-alpine grassland, frequently to heavily grazed, 26 Feb 2020, S.P. Sylvester et al. 3638 (PRE, US).

Notes.

Poa binata is a common species in the upper Maloti-Drakensberg mountains. In areas with enough moisture and low grazing pressure, the species can be the dominant grass species, forming dense tussocks to 0.5 m diameter. As in many large grass tussocks, a few shoots can appear to be rhizomatous, but are actually stooling shoots as in P. bidentata (see below). Under high grazing pressure, plants become smaller and weaker and sparsely distributed. Plants seem to tolerate burning well. The species displays unusual diversity in lemma pubescence, varying from glabrous to pubescent on three veins, to pubescent on five veins and sometimes between veins and callus hairs may be present or absent. Flowers are pistillate and/or perfect within plants, anthers are 1.5-2.7 mm long or vestigial. 2 n = 28, 42, 56. - Ha genotype (Gillespie and Soreng, unpublished).

The species exhibits a diclinous breeding system. Most species of Poa are hermaphroditic. Dicliny occurs in about one quarter of the species of Poa examined and ranges from simple gynomonoecy to full dioecy ( Soreng et al. 2020). In P. binata , many plants have spikelets with pistillate upper flowers. Other plants exhibit more pistillate flowers within spikelets and wholly pistillate spikelets. The latter are concentrated on the lower branches of panicles. Some plants were judged to be completely pistillate. The sterile rudiments of anthers (staminodes), present in pistillate flowers, are believed to result from genetic control, not from apomixis. All other florets, spikelets and sometimes whole plants examined were perfect-flowered. The breeding system of P. binata needs further study, but seems to match sequential gynomonoecy as described by Soreng and Keil (2003). This breeding system is estimated by RJS to occur in 28 species equally divided between the Americas and east Asia ( Soreng et al. 2020), almost all of which have anthers averaging 2 mm long or longer.

The lectotype at P is selected as it is one of two sheets with Drège’s original handwritten location and date, the other original set of tickets being destroyed ( Gunn and Codd 1981). The lectotype is clearly distinct from all the others, which may or may not be duplicates of the second collection cited by Nees ab Esenbeck (1841). Other syntypes or original material have only secondary notes from Ernst Meyer’s distribution of Drège sets (in 1837, 1840, 1847; Meyer 1837, 1840, 1847) or guessed at from other duplicates, some of which may actually have been collected by Zeyer (who joined the Drège brothers in 28 Nov 1832 into early December and then collected on his own for some months before departing South Africa, for example, the K000345193 sheet which originally said Zeyer, but that was crossed out and replaced by Dredge and a location where they collected together). For further reading, see Gunn and Codd (1981). Some of the other distributions say Tafelberg 6000-7000 ft [1829-2134 m], but these may be tertiary writings or collections not used in the protologue, as the protologue did not mention anything above 6000 ft [1819 m]. We have located various specimens:

…. 7/12 32. [7 Dec 1932] Unter den Hängen vom Los-Tafelberg, 5000-6000' [1524-1829 m], | b (I af. {original Drège label} (syntype, P000434747 [image!])

…. " Poa binata N.ab.E. a" {original ticket from E. Meyer distribution}, Los Tafelberg, in dem Kranzen und auf feuchten und felsigen, Bergplatte, 6000-7000 fuss [1829-2134 m], December, J.F. Drège {penned by someone} (E00200327 [image!])

…. " Poa binata N.ab.E. a" {original ticket from E. Meyer distribution} J.F. Drège {stamped on that}, in monte Tafelberg 6000' [1829 m], J. F. Drège {typed later} (HAL [image!])

…. " Poa binata N.ab.E. a" {original ticket from E. Meyer 1840 distribution}, Afr. Austr., Drège, 1840, {old note, year 1840 presumably referring to E Meyer distribution of Drège set}, Hb. Benth. Table Mountain, Queenstown Div. 6000-7000 ft {penned by someone} [1829-2134 m] (K000345242 [image!])

…. " Poa binata N.ab.E. a" {original ticket from E. Meyer distribution}, Poa binata N.ab.E., Gramin Africa p. 378 No 2., Africa Austr. Drège No. {original duplicate ticket from E. Meyer?} (BM ex hb. Shuttleworth)

…. " Poa binata N.ab.E. a 1840, 324" {original ticket from E. Meyer 1840 distribution}, "Los Tafelberg, in den Kranzen und auf der feuchten und felsigen Bergplatte, 6000-7000 fuss [1829-2134 m], December" {typed ticket} (S-C-4936)

…. " Poa binata N.ab.E. a" {original ticket from E. Meyer distribution}, 210 Poa binata N. ab. E. 117.11 ex Bernhardi herbarium (MO2112449 (bc) 2397251)

Poa bidentata Nees is usually placed in P. pratensis , but in our opinion, it is merely a stooling example of P. binata . It has lemmas that, in addition to having pubescence like P. pratensis , are quite scabrous in the margins and between the veins, ruling out P. pratensis . There are various sheets and fragments of P. atherstonei (= P. binata ) at PRE, collected by Ms. Pelger between 1901 and 1914, but only one that matches the date and cited by Hackel (1904). That one has lemmas that are glabrous or sparsely pubescent on the keel and marginal veins, web short and scant or absent.

Figures

Figure 1. Poa binata. A whole plants B basal part of plant showing fibrous basal sheaths C, D portions of inflorescence. Image A of S. P. Sylvester et al. 3489 (US) B of S. P. Sylvester et al. 3412 (US) C of S. P. Sylvester et al. 3518 (US) D of S. P. Sylvester et al. 3677 (US).