Lachenalia adamii G.D.Duncan, 2017

Duncan, Graham D., 2017, Two new species, two rediscoveries and a range extension in Lachenalia (Asparagaceae: Scilloideae) from southern and western South Africa, Phytotaxa 316 (3), pp. 261-270 : 266-269

Lachenalia adamii G.D.Duncan , sp. nov. ( Figs. 3–5 ).

Type:— SOUTH AFRICA. Northern Cape: Oorlogskloof Nature Reserve south of Nieuwoudtville (3119 AC), occasional on steep river banks east of Kareebos on Rock Pigeon hiking trail, in shale scree, elevation 600 m, 31.480°S, 19.093°E, 11 Sept. 2011, Harrower 4977 (holotype: NBG!; isotypes: NBG!, PRE!) .

This new species differs from L. latimeriae Barker (1979: 196) in having a subreclinate raceme of narrowly campanulate flowers with white outer tepals, translucent white and green inner tepals with the lower inner tepal diverging markedly from the two upper ones, weakly spreading filaments, a linear, reclinate or spreading leaf, the development of numerous bulblets around the base of the mother bulb, a broadly ellipsoid capsule, and a larger, matte black seed 1.8 × 1.6 mm with rugose secondary sculpturing and a longer strophiole 0.8 mm long.

Deciduous, winter-green geophyte, 130–195 mm high. Bulb ovoid, 12–15 mm in diam., bulblet- forming around base; tunic 2-layered, outer layer dark brown, inner layer thinner, light brown; cataphylls 2, membranous, tightly surrounding leaf base, apices translucent, obtuse, lower cataphyll 5 mm long, light brown, upper cataphyll 15 mm long, white. Leaf solitary, linear, 90–150 × 6–12 mm, spreading, reclinate, conduplicate in lower third, deeply canaliculate in upper two thirds, bright green, base maroon or marked with maroon transverse bands, apex attenuate; clasping base with light brownish purple transverse bands basally, shading to green distally. Inflorescence a subreclinate raceme, 4–20-flowered; peduncle 65–110 mm long, light green; bracts cup-shaped at base of inflorescence, becoming ovate above, 1 × 1–2 mm, translucent white; pedicels suberect, 5–9 mm long, white. Perianth zygomorphic, narrowly campanulate, cernuous, lightly spicy-scented; tube cup-shaped, 2 mm long, white; outer tepals narrowly ovate, 8–9 × 4–5 mm, white, margins straight, apex slightly recurved, apical gibbosity greenish brown; inner tepals obovate, 9–11 × 4–5 mm, weakly spreading when fully open, translucent white, apices recurved, lower tepal 1 mm narrower than upper two tepals and diverging markedly, apices recurved, median keels brownish green. Stamens exserted, filaments weakly spreading, 10–11 mm long, white, anthers oblong, 0.5 mm long, dull red prior to anthesis, pollen yellow. Ovary ovoid, 3 × 2 mm, light green; style declinate, 8–9 mm long, exserted, white; stigma minutely capitate. Capsule broadly ellipsoid, 8–9 × 6–7 mm. Seed globose, 1.8 × 1.6 mm, matte black, secondary sculpturing rugose; strophiole 0.8 mm long, ridged. Flowering time: late September to mid-October.

Etymology:— The specific epithet adamii honours Adam Harrower who discovered the species and made the first scientific collection of plants.

Notes:— The only known collection of this species was made by Kirstenbosch horticulturist Adam Harrower in the Oorlogskloof Nature Reserve south of Nieuwoudtville in September 2011. The plants were found in a vegetative state, and habitat photographs were taken. Bulbs were cultivated in a pot at Kirstenbosch National Botanical Garden, and when they flowered later that year, it became evident that they represented an undescribed species. Photographs of the flowering plants were taken. The following year a line drawing was prepared by Vicki Thomas, and the type material was pressed.

Diagnostic features and affinities:— Lachenalia adamii is recognised by a usually sparsely flowered, subreclinate raceme of cernuous, narrowly campanulate, translucent greenish white flowers with cup-shaped perianth tubes and protruding inner tepals with brownish green median keels. The inner tepals are weakly spreading when fully open, and the lower inner tepal diverges markedly from the two upper inner tepals ( Figs. 4 , 5 ). The flowers have exserted, narrowly spreading stamens, prominent, suberect pedicels, and bracts that are cup-shaped at the base of the inflorescence and become ovate above. It is further recognised by a solitary, linear, reclinate or spreading, green leaf, with the base maroon or lightly marked with maroon transverse bands, and the adult bulb forms bulblets basally ( Figs. 4 , 5 ). The seeds are globose and matte black with rugose secondary sculpturing and have ridged strophioles.

Lachenalia adamii is included in subgenus Lachenalia section Angustae due to its zygomorphic, narrowly campanulate perianth ( Duncan 2012). It appears closely allied to L. latimeriae , which is geographically widely separated in the southern Western Cape and southwestern Eastern Cape. Although L. latimeriae is placed in a different section (Oblongae) on account of its oblong-campanulate perianth, the overall appearance of the flowering plant most closely resembles that of L. adamii . Lachenalia latimeriae has a similar cernuous perianth with a cup-shaped tube, ovate outer tepals with greenish brown apical gibbosities, exserted stamens and prominent suberect pedicels; it differs in its 1 or 2, lanceolate, erect inflorescence, light pink to lilac, oblong-campanulate perianth with the lower inner tepal not diverging markedly from the upper inner tepals, and in its more or less straight stamens. It differs further in having obovoid capsules, smaller, glossy black seeds 0.9–1.0 × 1.3–1.4 mm without secondary sculpturing and a shorter strophiole 0.6 mm long. It flowers earlier than L. adamii , July to early September, and occurs in different vegetation types in Western and Eastern Little Karoo, Kouga Sandstone Fynbos and Gamtoos Thicket ( Duncan 2012).

Distribution and habitat:— Lachenalia adamii occurs within the Fynbos Biome and the Karoo Renosterveld Bioregion and is only known from the type collection east of Kareebos in the Oorlogskloof Nature Reserve south of Nieuwoudtville on the Bokkeveld escarpment ( Fig. 3 ). The plants grow among moss-covered rocks in shale scree in scattered small groups of up to 15 plants on steep, southwest-facing river banks below sandstone cliffs, at an elevation of 600 m, in Vanrhynsdorp Shale Renosterveld. This vegetation type has previously been noted for its lack of endemic geophytes ( Mucina & Rutherford 2006), and thus L. adamii appears to be an exception.Associated plant species include the dwarf geophyte Xenoscapa fistulosa (Spreng. ex Klatt 1863: 781) Goldblatt & Manning (1995: 172) ( Iridaceae ), the dwarf succulents Adromischus hemisphaericus ( Linnaeus, 1753: 429) Lemaire (1852: 60) ( Crassulaceae ) and Crassula tomentosa Thunberg (1778: 333) ( Crassulaceae ), and the shrub Stachys rugosa Aiton (1789: 303) ( Lamiaceae ).

Figures

FIGURE 3. Distribution of Lachenalia barbarae (black dot) in southern South Africa and Lachenalia adamii (black star) in western South Africa.

FIGURE 4. Lachenalia adamii, drawn from Harrower 4977. A. Flowering plant with bulblets. B. Single flower in lateral view. C. Dissected flower in lateral view. Scale bars: 10 mm. Illustration by Vicki Thomas.

FIGURE 5. Lachenalia adamii, view of plants leafing out in shale scree, Oorlogskloof Nature Reserve, northwestern Cape (A.) and flowering plants in cultivation (B.). Photographs by Adam Harrower.