Lachenalia granitica G.D.Duncan, 2023

Duncan, Graham D., 2023, Four new species and three taxonomic adjustments in Lachenalia (Asparagaceae: Scilloideae) from southern and western South Africa, Phytotaxa 585 (4), pp. 261-273 : 266-267

Lachenalia granitica G.D.Duncan , sp. nov. ( Figs. 1 , 2 )

Type: — SOUTH AFRICA. Western Cape: Vredenburg (3217 DD), among granite rocks immediately south of town, elev. 167 m, 6 August, 1962, Barker 9680 (holotype NBG!) .

This new species differs from L. longibracteata in having a spicate inflorescence with longer, metallic blue and often blue-spotted outer tepals (9–10 mm long), translucent white inner tepals, longer filaments (9–11 mm long), a shorter style (9–10 mm long), leaf upper surfaces that are often shallowly pustulate, a smaller globose seed (0.9–1.0 × 1.0 mm) with a shorter inflated strophiole (0.8 mm long), and a flowering period that begins much earlier in midwinter (late June).

Deciduous, winter-green geophyte 90–330 mm high. Bulb globose, 10–25 mm in diam., solitary; tunic multilayered, outer tunics spongy, dark brown, inner tunics membranous; cataphyll 10–32 × 10–15 mm, translucent white, apex obtuse. Leaf 1 or 2, lanceolate, 35–190 × 8–28 mm, suberect, dull green, upper surface usually smooth, rarely covered with flattened pustules; margins coriaceous; leaf bases clasping, 20–40 mm long, light green; primary seedling leaf prostrate, flat. Inflorescence spicate, 7–50-flowered, dense, peduncle erect or suberect, glaucous, plain or lightly green-spotted; bracts ovate at base of inflorescence, becoming lanceolate above, 2–25 × 3–5 mm, translucent white. Perianth zygomorphic, oblong-campanulate, suberect, sweet-scented; tube cup-shaped, 4–5 mm long, metallic blue or blue-green, plain or darker blue-spotted; tepals light metallic blue, plain or darker blue-spotted; outer tepals narrowly ovate, 9–10 × 3–4 mm, apical gibbosity brown or greenish brown; inner tepals obovate, 10–11 × 4–5 mm, translucent white, fading to brownish maroon, apices obtuse, slightly recurved, median keels bright green. Stamens included or shortly exserted; filaments declinate, 9–11 mm long, white; anthers oblong, 1 mm long, pollen yellow. Ovary ellipsoid, 3 × 2 mm, dull green; style declinate, 9–10 mm long, white, becoming strongly exserted in fruit; stigma minutely capitate. Capsule ellipsoid, 8–10 × 5–6 mm. Seed globose, 0.9–1.0 × 1.0 mm, matt, black, secondary sculpturing rugose; strophiole inflated, 0.8 mm long, smooth, glossy black. Flowering time: June to September.

Etymology:— The specific epithet granitica refers to the granite rocky outcrops and granitic flats of the Cape West Coast, to which this species is endemic.

Other material examined:— SOUTH AFRICA. Western Cape: Witklip south of Vredenburg (3217 DD) , 9 August 1984, Barker 10250 ( NBG) ; granite outcrop south of Vredenburg , off R399 (3217 DD) , among houses, in loamy clay soil, westerly aspect, 20 June 2006, elevation 167 m, Cowell & Nurrish 537 ( NBG) ; Stompneus, northwest of St. Helena Bay (3217 DD) , 27 June 1967, Hall 3139 ( NBG) ; above Stompneus (3217 DD) , 17 June 1965, Barker 10567 ( NBG) . Nooitgedacht Farm near St Helena Bay (3218 CC) , 28 June 1972, Barker 10228 ( NBG) . Entrance to Saldanha off R399, on granite hill above town (3317 BB) , occasional in loamy clay on west-facing rocky slope, 9 October 1983, Duncan 119 ( NBG) . Langebaan (3318 AA) , 21 July 1938, Lewis s.n. sub. NBG 222/32 ( NBG) . Darling (3318 AD) , 23 August 1947, Barker 4599 ( NBG) ; Waylands Farm Flower Reserve east of Darling (3318 AD) , 8 September 1974, Barker s.n. ( NBG, photo.) .

Notes:— The earliest known collection of L. granitica is that of G.J. Lewis who recorded it in flower at Langebaan on the Cape West Coast on 21 July, 1938. Most collections have been made in the vicinity of Vredenburg to the north. The species is becoming increasingly threatened by coastal housing development.

Diagnostic features and affinities:— Lachenalia granitica is recognised in flower by a dense spike of suberect, oblong-campanulate, sweet-scented flowers with metallic blue or blue-green perianth tubes, light metallic blue outer tepals which may be plain or darker blue-spotted, and protruding, translucent white inner tepals with obtuse, slightly recurved apices. The outer tepals have a prominent brown or greenish brown apical gibbosity, and the inner tepals have bright green median keels and fade to brownish maroon ( Fig. 1 G, H, I ). Each flower is subtended by a prominent lanceolate, translucent white bract, and in the upper part of the inflorescence the bracts may be up to 25 mm long ( Fig. 1 G ). The plant produces one or two lanceolate, dull green, suberect leaves with coriaceous margins, mostly with smooth surfaces, or rarely with sporadic flattened pustules. The ripe fruit is an ellipsoid capsule containing globose, matt, black seeds with an inflated, smooth, glossy strophiole.

Lachenalia granitica is a member of sect. Lachenalia , subsect. Lachenalia ( Duncan et al. 2022) . Due to its prominent floral bracts, and similar oblong-campanulate flowers, it has previously been regarded as a blue-flowered form of L. longibracteata ( Duncan 2012) , however in phylogenetic analysis it was retrieved as sister to the turquoise, tubular-flowered L. viridiflora Barker (1972: 179) (with which it occurs sympatrically on granite outcrops in northern parts of its Cape West Coast range), within the uppermost clade of subsect. Lachenalia ( Duncan et al. 2022) . L. longibracteata differs from L. granitica in having a racemose inflorescence with shorter, greenish yellow outer tepals (6–9 mm long), shorter filaments (7–9 mm long), a longer style (11–14 mm long), leaf upper surfaces that are always smooth, a larger globose seed (1.1 × 0.9 mm) with a longer inflated strophiole (1.0 mm long) and a later flowering period from early to late spring (late August to mid-October).

Distribution and habitat:— Lachenalia granitica occurs in the Fynbos Biome and is confined to the Cape West Coast, extending from Darling in the south to St. Helena Bay in the north ( Fig. 2 ). It is endemic to granite outcrops and flats, occurring among low scrub in partially shaded aspects within boulder crevices in dark brown, loamy soils in Saldanha Granite Strandveld, and in open aspects on granite flats, in Swartland Granite Renosterveld ( Mucina & Rutherford 2006). The plants occur as scattered solitary individuals or in small groups, and when in flower, are inconspicuous among surrounding vegetation. Flowering commences in mid-winter and ends in early spring (late June to early September). Near Vredenburg, the flowerheads are grazed by steenbuck ( Raphicerus campestris ) and in winter the bulbs are excavated and eaten by Cape porcupines ( Hystrix africaeaustralis ) ( Duncan 2012).

Figures

FIGURE 1. Lachenalia komsbergensis: detail of three flowering racemes in cultivation (A); single plant flowering in beige alluvium, Komsberg Pass (B); general view of Central Mountain Shale Renosterveldhabitat, Komsberg Pass (C).Lachenalia inflata: single flowering plant in red sand north of Middelpos (D); single flowering plant in red clay west of Calvinia (E); general view of Roggeveld Karoo habitat north of Middelpos (F). Lachenalia granitica: detail of flowering spike in cultivation, with arrow showing a very long bract (G); flowering plant from Vredenburg in cultivation (H); spike of flowering and fruiting plant in Saldanha Granite Strandveld habitat near Vredenburg (I). Lachenalia filamentosa: flowering plants from Riviersonderend in cultivation (J); single flowering plant from De Hoop Nature Reserve in cultivation (K); two plants in early fruiting stage in De Hoop Limestone Fynbos habitat, De Hoop Nature Reserve (L). Photographs: A-D, F-K by Graham Duncan; E by Adam Harrower; L by David Gwynne-Evans.

FIGURE 2. Distribution of Lachenalia komsbergensis in the southern Great Karoo of the Northern Cape, South Africa (inverted black triangle), Lachenalia inflata in the western Great Karoo, Northern Cape, South Africa (black triangles), Lachenalia granitica along the Cape West Coast, Western Cape, South Africa (black squares) and Lachenalia filamentosa along the Cape West Coast, Breede River Valley and Overberg in the Western Cape, South Africa (black dots).