New species and notes on Hesperantha ( Iridaceae ) in southern Africa

Field studies o f the sub-Saharan African and largely southern African Hesperantha conducted since 2003 have resulted in the discovery o f three new species in this genus, bringing the total to 82. Hesperantha longistyla J.C.Manning & Goldblatt. known from one collection from the mountains o f SW Namibia, is a dwarf plant with moderately long-tubed, purple flowers and unusually long style branches, possibly allied to the Kamiesberg species, H. latifolia. A second species, H. helmei Goldblatt & J.C.Manning, also known from a single collection from the interior mountains o f Eastern Cape near GraaffReinet, has terete leaves and small flowers with tepals ± 8 x 2.5 mm, about as long as the perianth tube. It is apparently most closely allied to the Roggeveld species, H. d lio la ta . A third novelty, H. lithicola J.C.Manning & Goldblatt. restricted to the Swartruggens range in the eastern Cold Bokkeveld, has bell-shaped corms with toothed margins, leaves 1-2 mm wide, and white flowers with a tube 10-12 mm long, and appears most closely allied to the widespread H. falcata. A new collection o f H karooica from northeast o f the Hantamsberg represents a small but significant range extension for this local endemic previously known from just two collections near Calvinia, south o f these mountains. The flower size, especially dimensions o f the tepals, confirms its status as a separate species allied to H. vaginata. Lastly, new collections o f the relatively uncommon, yellow-flowered variant o f H. acuta show that this plant, confined to the eastem portion o f the range o f the species, differs consistently from the white-flowered form in several floral features, and it is raised to subspecies rank as H. acuta subsp. tugHelliae. INTRODUCTION TAXONOMY Hesperantha Ker Gawl. (Iridaceae: Crocoideae) is dis­ tributed across sub-Saharan Africa but is most diverse and species-rich in southern Africa. The genus has two cen­ tres of diversity here, the winter rainfall west (Goldblatt 1984), and the coast and adjacent mountains of the east­ em, summer rainfall half of the subcontinent (Hilliard & Burtt 1986). In the most recent revision of the genus, 79 species were recognized (Goldblatt 2003). Although Hesperantha is now well understood taxonomically, three collections made since the publication of this revision represent novelties, all from areas of southern Africa that are poorly collected. We describe them here. In addition, a new collection and important range exten­ sion of the poorly known H. karooica Goldblatt confirm that flower size, especially dimensions of the tepals, con­ sistently differs from that in the closely allied H. vagi­ nata (Sweet) Goldblatt, removing doubts about its status as merely a depauperate form of the latter. In H. acuta new collections have provided convincing evidence that the eastem, yellow-flowered populations of the species consistently have larger flowers that differ in several additional features from the westem, white-flowered populations. The yellow-flowered populations clearly constitute a separate race of the species, which we recog­ nize as H. acuta subsp. tugwelliae. The total number of species in Hesperantha is thus increased to 82: 43 of these occur in the southem African winter rainfall zone; 39 in the southem African summer rainfall zone south of the Limpopo; and four in tropical Africa. * B.A. KrukofT Curator o f African Botany, Missouri Botanical Garden, RO. Box 299, St. Louis, Missouri 63166, USA. E-mail: peter.goldblatt@mobot.org. ** Compton Herbarium. South African National Biodiversity Institute, Private Bag X7, 7735 Claremont, Cape Town. E-mail: manning@sanbi.org. MS. received: 2007-01-09. Hesperantha \onghXy\2L J.C.Manning & Goldblatt, sp. nov. Plantae ± 30 mm altae, cormo campanulato ± 10 mm diam. margine spinis radiatis armato, caule ad 8 mm longo, foliis 3 falcatis 30-50 x 2.5-3.0 mm, spica 1vel 2-flora, bracteis viridibus 7-10 mm longis, floribus manifeste purpureis ad faucem tubi flavis, tubo perianthii 20-25 mm longo, tepalis subaequalibus anguste ovatis patentibus, staminibus adscendentibus, antheris ± 5 mm longis, ramis styli ± 10 mm longis laxe patentibus. TYPE.—Namibia, 2716 (Witputz): south of Sebrafontein, 1 400 m, (-DD), 28 August 2003, P. Bruyns 9484A (NBG, holo.). Plants ± 30 mm high; corm bell-shaped with flat base, ± 10 mm diam. at base, margin with radiating spines. Stem reaching up to 8 mm above ground, unbranched. Leaves 3, falcate, 30-50 x 2.5-3.0 mm; cataphylls mem­ branous. Spike 1or 2-flowered; bracts green, 7-10 mm long, outer about as long as inner or slightly longer, inner forked at apex. Flowers evidently purple, yellow in mouth of tube; perianth tube 20-25 mm long, slender, widening near apex; tepals subequal, narrowly ovate, ± 10 X 6 mm, outer slightly wider than inner, spreading horizontally. Stamens symmetrically disposed, slightly spreading; filaments ± 4 mm long, exserted ± 3 mm from tube; anthers ± 5 mm long. Ovary ovoid, ±1.5 mm long; style dividing at mouth of perianth tube, branches ± 10 mm long, spreading laxly. Capsules and seeds unknown. Flowering time: mid-August to early September. Figure lA. Distribution and ecology: found in rock crevices at higher elevations in the mountains of southwestern 178 Bothalia 37,2 (2007) Namibia near Rosh Pinah, in the winter rainfall part of that country (Figure 2). Plants were growing among dolomite rocks and in crevices on the summit of a high ridge, where they would have benefited from any addi­ tional moisture that condensed from sea fog. It is likely that the species occurs elsewhere in suitable places in this rugged, largely inaccessible, and botanically poorly explored region. Known only from the type collection, made by Cape Town succulent specialist Peter Bruyns in 2003, Hesperantha longistyla is a surprising discovery, representing the only species of the genus known from Namibia. FIGURE 1.—A, Hesperantha longi­ styla, Bruyns 9484A\ B, H. helmei, Helme 3144. Scale bars: 10 mm. Artist; J.C. Manning. Diagnosis and relationships', distinctive in its short stature, falcate leaves, relatively long perianth tube, 2025 mm long, and disproportionately long style branches, Hesperantha longistyla has the bell-shaped corm with a flat base that characterizes a handful of other species in the genus from the southern African winter rainfall zone to the south, including white-flowered H. falcata (L.f) Ker Gawl. as well as the two purple-flowered species, H. latifolia (Klatt) M.P.de Vos and H. panciflora (Baker) G.J.Lewis. The last two species occur in Namaqualand, the fornier restricted to the Kamiesberg and the latter reaching its northern limit there, well to the south of Bothalia 37,2 (2007) 179 FIGURE 2.— Known distribution o f Hesperantha longistyla. A ; H. helmei, tugweUiae, • . k; H. Uthicola, ■ ; H. acuta subsp. acuta, O; and H. acuta subsp. Namibia. Nevertheless, the proximity of their ranges, and their similar flower colour suggest that H. longistyla is allied to these two species. H. longistyla is most simi­ lar to the long-tubed H. latifolia but differs in its smaller flowers, with tepals ± 10 mm long, and in the marked difference in the relative proportions of stamens and style. The filaments in H. longistyla are relatively short, 3-4 mm long and the style branches project ± 3 mm beyond the tips of the anthers, thus appearing unusually long. The flowers of H. latifolia, in contrast, are gener­ ally much larger, with tepals 15-23 mm long, the fila­ ments (4-) 7-10 mm long, and the style branches do not extend much beyond the tips of the anthers. Hesperantha helmei Goldblatt & J.C.Manning, sp. nov. Plantae 180-250 mm altae, cormo globoso asymmetrico ± 9 mm diam., caule eramoso in quarta superiore folium squamiformem gerente, foliis 3, inferioribus dua teretibus costatis, superiore vaginanti, spica 1vel 2-flora, bracteis viridibus, ± 9 mm longis, floribus pallide malvinis, tubo perianthii 6-8 mm longo, tepalis subequalibus anguste ovatis ± 8 x 2.5 mm patentibus, filamentis ex tubo ± 2 mm exsertis, antheris ± 4 mm longis, ramis styli ±3.5 mm longis. TYPE.— South Africa, Eastern Cape, 3224 (GraaffReinet): ± 50 km E of Graaff-Reinet, upper northern slopes of Nardouwsberg, 1 km N of main peak, Annex Stijlfontein 250, 2300' [700 m], (-BB), 19 November 2004, N.A. Helme 3144 (NBG, holo.). Plants 180-250 mm high; corm globose, ± 9 mm diam., asymmetric, with concentric tunics. Stem slen­ der, unbranched, bearing short, scale-like leaf in upper fourth. Leaves 3, lower 2 terete, conspicuously grooved, blades 8-15 x 1.2 mm, uppermost leaf sheathing lower half to two thirds of stem; cataphylls membranous. Spike 1 or 2-flowered; bracts green, ± 9 mm long, inner about as long as outer and forked at apex. Flowers pale mauve. darker at mouth of tube, outer tepals with broad purple streak on reverse; perianth tube 6-8 mm long, slender, widening near apex; tepals subequal, narrowly ovate, ± 8.0 X 2.5 mm, outer slightly larger than inner, spread­ ing slightly above horizontal. Stamens symmetrically disposed, slightly spreading; filaments exserted ± 2 mm from tube; anthers ± 4 mm long. Ovaiy ovoid, ± 2 mm long; style dividing at mouth of perianth tube, branches ± 3.5 mm long, ascending, ultimately reaching to about middle of anthers. Capsules and seeds unknown. Flowering time: November and probably December. Figure IB. Distribution and ecology, apparently restricted to the southern edge of the interior escarpment, where it is known from a single collection made at high elevations in rocky grassland in the Sneeuberge, east of GraaffReinet (Figure 2). The plants were found in open areas in Merxmuellera grassland among dolerite boulders. These grasslands bum regularly every few years during the dry season and are regularly covered with snow in winter (N.A. Helme pers. comm.) The tips of the long, basal leaves in all the specimens have been burned or frosted off, indicating that the species begins leafing early in the


INTRODUCTION TAXONOMY
Hesperantha Ker Gawl.(Iridaceae: Crocoideae) is dis tributed across sub-Saharan Africa but is most diverse and species-rich in southern Africa.The genus has two cen tres of diversity here, the winter rainfall west (Goldblatt 1984), and the coast and adjacent mountains of the east em, summer rainfall half of the subcontinent (Hilliard & Burtt 1986).In the most recent revision of the genus, 79 species were recognized (Goldblatt 2003).Although Hesperantha is now well understood taxonomically, three collections made since the publication o f this revision represent novelties, all from areas o f southern Africa that are poorly collected.We describe them here.In addition, a new collection and important range exten sion o f the poorly known H. karooica Goldblatt confirm that flower size, especially dimensions of the tepals, con sistently differs from that in the closely allied H. vagi nata (Sweet) Goldblatt, removing doubts about its status as merely a depauperate form of the latter.In H. acuta new collections have provided convincing evidence that the eastem, yellow-flowered populations of the species consistently have larger flowers that differ in several additional features from the westem, white-flowered populations.The yellow-flowered populations clearly constitute a separate race o f the species, which we recog nize as H. acuta subsp.tugwelliae.The total number of species in Hesperantha is thus increased to 82: 43 of these occur in the southem African winter rainfall zone; 39 in the southem African summer rainfall zone south of the Limpopo; and four in tropical Africa.
Distribution and ecology: found in rock crevices at higher elevations in the mountains of southwestern Namibia near Rosh Pinah, in the winter rainfall part of that country (Figure 2).Plants were growing among dolomite rocks and in crevices on the summit of a high ridge, where they would have benefited from any addi tional moisture that condensed from sea fog.It is likely that the species occurs elsewhere in suitable places in this rugged, largely inaccessible, and botanically poorly explored region.Known only from the type collection, made by Cape Town succulent specialist Peter Bruyns in 2003, Hesperantha longistyla is a surprising discovery, representing the only species of the genus known from Namibia.Diagnosis and relationships', distinctive in its short stature, falcate leaves, relatively long perianth tube, 20-25 mm long, and disproportionately long style branches, Hesperantha longistyla has the bell-shaped corm with a flat base that characterizes a handful of other species in the genus from the southern African winter rainfall zone to the south, including white-flowered H. falcata (L .f)Ker Gawl.as well as the two purple-flowered species, H. latifolia (Klatt) M.P.de Vos and H. panciflora (Baker) G.J.Lewis.The last two species occur in Namaqualand, the fornier restricted to the Kamiesberg and the latter reaching its northern limit there, well to the south of Namibia.Nevertheless, the proximity of their ranges, and their similar flower colour suggest that H. longistyla is allied to these two species.H. longistyla is most simi lar to the long-tubed H. latifolia but differs in its smaller flowers, with tepals ± 10 mm long, and in the marked difference in the relative proportions of stamens and style.The filaments in H. longistyla are relatively short, 3-4 mm long and the style branches project ± 3 mm beyond the tips of the anthers, thus appearing unusually long.The flowers of H. latifolia, in contrast, are gener ally much larger, with tepals 15-23 mm long, the fila ments (4-) 7-10 mm long, and the style branches do not extend much beyond the tips of the anthers.
Plantae 180-250 mm altae, cormo globoso asymmetrico ± 9 mm diam., caule eramoso in quarta superiore folium squamiformem gerente, foliis 3, inferioribus dua teretibus costatis, superiore vaginanti, spica 1-vel 2-flora, bracteis viridibus, ± 9 mm longis, floribus pallide malvinis, tubo perianthii 6-8 mm longo, tepalis subequalibus anguste ovatis ± 8 x 2.5 mm patentibus, filamentis ex tubo ± 2 mm exsertis, antheris ± 4 mm longis, ramis styli ± 3.5 mm longis.Plants 180-250 mm high; corm globose, ± 9 mm diam., asymmetric, with concentric tunics.Stem slen der, unbranched, bearing short, scale-like leaf in upper fourth.Leaves 3, lower 2 terete, conspicuously grooved, blades 8-15 x 1.2 mm, uppermost leaf sheathing lower half to two thirds o f stem; cataphylls membranous.Spike 1 -or 2-flowered; bracts green, ± 9 mm long, inner about as long as outer and forked at apex.Flowers pale mauve.darker at mouth of tube, outer tepals with broad purple streak on reverse; perianth tube 6-8 mm long, slender, widening near apex; tepals subequal, narrowly ovate, ± 8.0 X 2.5 mm, outer slightly larger than inner, spread ing slightly above horizontal.Stamens symmetrically disposed, slightly spreading; filaments exserted ± 2 mm from tube; anthers ± 4 mm long.Ovaiy ovoid, ± 2 mm long; style dividing at mouth o f perianth tube, branches ± 3.5 mm long, ascending, ultimately reaching to about middle of anthers.Capsules and seeds unknown.Flowering time: November and probably December.Distribution and ecology, apparently restricted to the southern edge of the interior escarpment, where it is known from a single collection made at high elevations in rocky grassland in the Sneeuberge, east of Graaff-Reinet (Figure 2).The plants were found in open areas in Merxmuellera grassland among dolerite boulders.These grasslands bum regularly every few years during the dry season and are regularly covered with snow in winter (N.A. Helme pers.comm.)The tips o f the long, basal leaves in all the specimens have been burned or frosted off, indicating that the species begins leafing early in the growing season when the danger of fire or frost is not yet over.
Diagnosis and relationships: Hesperantha helmei is named for its discoverer, the Cape Town ecologist and energetic and wide-ranging plant collector, N.A. Helme.The species is distinctive in its relatively small, pale mauve flower with a perianth tube 6-8 mm long, narrow tepals ± 8.0 x 2.5 mm, and terete, finely ribbed leaves.Another unusual attribute of the species is the small, sheathing, scale-like leaf in the upper part o f the stem.This distinctive feature is characteristic of a small group of species allied to H. pilosa (L.f.) Ker Gawl., all native to the winter rainfall zone of southern Africa.Among these species, H. pilosa is largely a species o f the Cape floristic region, whereas H. ciliolata Goldblatt, H. teretifolia Goldblatt and the hairy-leaved H. pseudopilosa Goldblatt are centred on the Roggeveld Escarpment of the Western Karoo (Goldblatt 1987).Among the spe cies in this group, H. helmei is probably most closely related to H. ciliolata and H. teretifolia, which also have terete, prominently ridged leaves, the grooves lined with fine ciliate hairs that are absent in H. helmei.The flow ers of H. ciliolata and H. teretifolia are slightly larger than those of H. helmei, with a perianth tube ± 8 mm long and tepals ± 10 mm long.Hesperantha teretifolia in particular is broadly similar to H. helmei in general appearance, but has minutely ciliolate leaf ribs, a small, scale-like leaf, 2-4 mm long, and larger anthers, ± 8 mm long.H. helmei, in contrast, has glabrous leaves, a larger scale-like leaf, 8-10 mm long, and smaller anthers, ± 4 mm long.
While the presence o f an endemic species of Hespe rantha in the Sneeuberge is surprising, it is not without precedent in the Iridaceae.A handful of species of the family occur there, including taxa from both the winter rainfall zone to the west and the summer rainfall zone to the east.Those from the winter rainfall zone include Moraea ciliata, M. crispa and M imguiculata.The Iridaceae from the summer rainfall zone include one Dierama species, Romulea macowanii, three species of Syringodea, including the near endemic S. pulchella, and a distinctive short, broad-leaved form of Babiana bainesii.This mix of summer and winter rainfall species reflects the transitional position of these mountains, that have a grassland-dominated flora characteristic of the summer rainfall region at higher elevations but which receive predictable amounts of winter rainfall that permit the persistence of a handful of species from the winter rainfall zone to the west.
Distribution and ecology': known from sandstone rock pavement in the Swartruggens Mountains in the eastern Cold Bokkeveld, where the plants grow in rock crevices or shallow humus, often in the shelter of small shrubs (Figure 2).
Diagnosis and relationships'.Hesperantha lithicola is distinctive in its symmetrical, bell-shaped corm and narrow, often twisted or coiled leaves.It is probably most closely allied to H. falcata, which it resembles in general appearance, but from which it differs in its con sistently narrower leaves, 1-2 mm wide (vs.4-8 mm in H. falcata), and longer perianth tube, 10-12 mm vs. 4-9 mm.The two species differ also in their habitats.Hesperantha lithicola is restricted to shallow soils on sandstone rock pavement, whereas H. falcata is a com mon and widespread species of seasonally moist, deeper clay or sandy soils.This ecological difference is very evident at the type locality, where H. falcata occurs on sandy flats not far from rocky outcrops to which H. lithi cola is restricted.
Hesperantha lithicola is remarkably similar in gen eral appearance to H. acuta (Licht.ex Roem.& Schult.)Ker Gawl.but this species has an asymmetrical corm with one side flattened and extended downward.Without corms, however, the two taxa are essentially indistin guishable, although H. acuta does not occur on the Cold Bokkeveld and is typically found on clay soils, rarely limestone or in pockets of loam on sandstone outcrops.

Hesperantha karooica Goldblatt
Known from just a handful of plants collected at two locations around Calvinia in Northern Cape, Hesperantha karooica is recognized among the species of the genus with large, asymmetric corms with overlapping tunics by its low stature, 30-50 mm high, and spikes of 1 or 2 yellow flowers with a tube ± 5 mm long and tepals ± 20 mm long (Goldblatt 1984(Goldblatt , 2003)).In general aspect the species is very like the more widespread Bokkeveld Plateau species, H. vaginata (Sweet) Goldblatt, which is normally taller, 120-180 mm high, and has spikes of (1)2-4 yellow flowers, usually marked with contrasting brown markings in the centre and on the tips of the outer tepals.Plain yellow-flowered plants are ^o w n from a few sites but both these and plants with marked tepals have a perianth tube 5-8 mm long and tepals 30-35 x 15-17 mm.Although the two species have been recog nized in recent revisions o f the genus (Goldblatt 1984(Goldblatt , 2003)), there has remained some doubt as to whether they are really distinct.
New collections of Hesperantha vaginata from near Loeriesfontein and of yellow-flowered plants that accord with H. karooica from well to the east o f Calvinia, con tribute to our understanding of the two taxa.The latter population, found some 50 km NNE o f Calvinia on the road to Klipwerf in the area known as the Agter Hantam {Goldblatt & Porter 12747), consists o f plants with bright yellow flowers, the outer tepals shaded brown out side, and ranging in height from 50 to 100 mm, with one plant found in the shade of a low shrub attaining a height of 160 mm.The flowers have a perianth tube 6-7 mm long, thus longer than until now reported for H. karoo ica and matching H. vaginata, but the tepals are ± 20 X 9-10 mm long and the anthers ± 10 mm long, thus ± as recorded for the two other collections o f H. karooica (Goldblatt 1984).
The collection of Hesperantha vaginata from near Loeriesfontein {Goldblatt & Porter 12775), from the Farm Rietfontein, and which comprises a modest range extension (Goldblatt 1984), consists of plants 50-120 mm high, the smallest of these unusual for the species.All individuals have flowers with the brown markings on the inside of the tepals that are typical of the species and anthers that are ± 12 mm long and tepals 30 x ± 12 mm.Even the smallest plants have flowers typical of the species.
We conclude that plant height and perianth tube length are not factors that consistently distinguish the two species, but that anther length and tepal size always differ.The tepal size especially is substantially smaller in Hesperantha karooica.Both this species and H. vaginata typically grow on heavy red clay derived from dolerite, although populations of H. vaginata from the west of its range also occur on tillite-derived clay or a mix of clay and sand derived from Table Mountain Sandstone 2 mm below to 1 mm above anther tips filaments are exserted 1.5-2.5 mm from the tube and that the style branches reach from ± 2 mm below the anther tips to 1 mm above them.The tube itself is 8.5-12.0mm long and the tepals 9.5-16.0mm long (Table 1).Plants with flowers falling in the upper range of these dimen sions are most common along the Cederberg but also occur over the entire range of the white-flowered variant of the species (Figure 2).Smaller-flowered plants occur mainly in the northwest of the range, along the foothills of the Bokkeveld and Matsikamma-Gifl^erg Mountains.Yellow-flowered plants, referred by R.C. Foster (1948) to H. tugwelliae, occur in the east of the range of H. acuta, in the northern foothills of the Swartberg Mountains, along the Kammanassie Mountains, and in the Long Kloof to the south in the vicinity of Joubertina (Figure 2).New collections made since 2002 (listed below) show that plants have a perianth tube 12.5-15.0mm long and tepals 12.5-16.0mm long, thus closely matching the white-flowered plants, but the filaments are exserted ± 4 mm and the anthers are 6 -8 mm long, whereas the style branches reach only to about the middle of the anthers (Table 1).
These consistent differences in the dimensions of anthers and style provide proof, in addition to flower colour, that the eastern populations constitute a sepa rate, larger-flowered race, and we believe it is useful to recognize the yellow-flowered populations as a separate taxon.Because of the small differences between the two, and complementary geographic ranges, we recommend subspecies rank for the taxon, and thus make the combi nation H. acuta subsp.tugwelliae.
Figure IB.
Hesperantha acuta (Licht.ex Roem.& Schult.)Ker Gawl.New and well-preserved collections o f the yellowflowered variant o f Hesperantha acuta(Goldblatt 1984), until now believed to be rare, have provided us with additional information about the species.Typical whiteflowered H. acuta is common in the western Karoo, and blooms prolifically in years o f adequate rainfall.The flowers, including the anthers, are white, although the outer tepals are brown to red on the outside.Careful measurements o f the stamens and styles show that the TABLE 1.-Comparison o f yellow-and white-flowered variants o f Hesperantha acuta.Only well-pressed, fully open flowers were