Eriospermum adpressifolium O.Weber

Weber, O., von Blittersdorff, R. & Beentje, H. 2015. Eriospermum adpressifolium (Asparagaceae) and Emilia blittersdorffii (Asteraceae) — two new species from Tanzania with nearly identical leaves. Kew Bulletin 70: 28. DOI https://doi.org/10.1007/s12225-01

Morphology General Habit

Tuberous geophyte with leaves appearing after flowering

Vegetative Multiplication Tubers

Tubers globose or elongate, multiple with age; simple tuber to 1.5 – 5 cm high, to 2.5 cm wide; skin brown, interior red at maturity, sometimes creamy white when young; growing point apical

Morphology Leaves

Leaves solitary, glabrous, appressed to the ground; contemporary leaf sheath not exserted; lamina appressed to the soil surface, ovate to broadly circular with a cordate base, up to 2.5 cm from the apex to the sheath insertion and up to 3.1 cm from apex to lobes, up to 3.4 cm wide; apex rounded and apiculate or acute; both surfaces green usually with a maroon margin, glabrous Old leaf sheaths remaining as brown coarse fibres, up to 3 cm long, below ground level

Morphology Reproductive morphology Inflorescences

Inflorescence up to 11 cm high (from the tuber to apex), entirely glabrous Raceme 1.3 – 5 cm long, to 2.7 cm wide, with 5 – 15 flowers

Morphology Reproductive morphology Inflorescences Bracts

Peduncular bract up to 2 cm long, sometimes exserted from ground level by up to 5 mm, membranous and somewhat transparent-white when dry, glabrous, apex sometimes reddish, not expanded Floral bracts about 1 mm long

Morphology Reproductive morphology Inflorescences Peduncles

Peduncle 5.1 – 7.4 cm long, about 1.5 mm diam. when fresh, dark red towards the base above ground level and becoming green to glaucous green usually with dark red speckles above

Morphology Reproductive morphology Flowers Pedicel

Pedicels erecto-patent, lowest up to 10 mm long at anthesis, green with maroon speckles

Morphology Reproductive morphology Flowers

Flowers rotate when fully open

Morphology Reproductive morphology Flowers Perianth

Tepals subequal, narrowly oblong to oblong-elliptic or oblong-lanceolate, free almost to the base (fused for less than 1 mm), 3.7 – 6.6 mm long, 1.0 – 1.7 mm wide, yellow inside, outside yellowish green basally and with a dark green to maroon midnerve and apex

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens erect, equal; filaments adnate to the tepals for ± 0.5 mm, filiform, yellow, ± 3 mm long; anthers ovoid, < 1 mm long, yellow

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary broadly ovoid, 1.2 – 1.7 mm long, very pale green

Morphology Reproductive morphology Flowers Gynoecium Style

Style 1.9 – 3.1 mm long, white

Morphology Reproductive morphology Fruits

Capsules not observed

Distribution

Only known from SW Tanzania. Map 2.

Ecology

Grows together with Emilia blittersdorffii; see habitat notes for that species.

Conservation

Based on herbarium material and sight records, Eriospermumadpressifolium falls into three subpopulations across a narrow area between Sumbawanga and Lake Rukwa, on the eastern slopes of the mountain range. The EOO is 20.5 km2, which is below the threshold for Critically Endangered (CR); the AOO is 14.97 – 20 km2 (cell size 1.72 – 2 km2), which is below the threshold for Endangered. The EOO and AOO were calculated using the GeoCat tool (Bachman et al. 2011). 2 km2 is the cell size used for narrow endemics by the East African Plant Redlisting Authority of IUCN and 1.72 km2 is a cell size suggested by the GeoCat tool based on the longest diameter of the EOO polygon. The biggest subpopulation, where the species has been recorded multiple times, is within 10 km of Sumbawanga, the capital of Rukwa region. The meadows near Ponda (currently a small village of ±400 inhabitants) in particular are at risk of land use change (being turned into maize fields). The locality at Malonje (about 13 km SSE of Ponda) is thought to be safer because of geological conditions unfit for agricultural exploitation. It is likely that additional suitable habitat exists in the region. Applying the Categories and Criteria of IUCN (2012), we assess this taxon as Endangered EN B1 ab (iii) + B2 ab (iii), with a decline in the quality of the habitat likely to affect two of its three subpopulations.

Note

The centre of diversity of Eriospermum is in Southern Africa (102 species), and only three species occur in Tropical East Africa (Govaerts 2014). E. adpressifolium is easily distinguished from these by its appressed leaf. An interactive key based on Perry’s revision (1994) is accessible online (Weber 2014).

This taxon belongs to subgenus Ligulatum, section Ligulatumsensu Perry (1994) which comprises 15 species of which 14 are endemic to Namibia or the winter-rainfall area of the Cape in South Africa, and Eriospermumabyssinicum Baker which is widespread elsewhere in Africa. Section Ligulatum is characterised by flowers with ligulate and equal to subequal tepals (as opposed to subgenus Eriospermum which has dimorphic tepals, and subgenus Cyathiflorum has spathulate tepals that form a distinct cup together with the stamens); the flowers occur before the leaves (unlike section Synanthum) and lack a large leaf-like peduncular bract (unlike section Grandibracteatum); the leaf is well developed (unlike section Photopedicellatum) and lack the typical enations of section Thaumazum. E. adpressifolium differs from other species in section Ligulatum with an apical growing point and yellow flowers by the circular-cordate leaf appressed to the ground level (as opposed to E. abyssinicum, E. macgregorium P. L. Perry, E. fragile P. L. Perry and E. schlechteri Baker which have erect, suberect or erecto-patent leaves with lanceolate, elliptic laminas; and E. citrinum P. L. Perry with an erecto-patent leaf and broadly ovate to circular-cordate lamina held off the ground level), and the smaller flowers (3.7 – 6.6 × 1.0 – 1.7 mm as opposed to ±8 × 2.0 – 2.5 mm in E. lavranosii P. L. Perry, which does have a prostrate leaf though not glabrous).

Eriospermumadpressifolium has been observed in flower from October to November. The onset of flowering is probably variable from year to year with the onset on rains. Leafing period: November to April.

The specific name highlights the habit of the plants in leaf, which it shares with its neighbour, Emilia blittersdorffii. The appressed leaf habit is found in several other Eriospermum species. This is the only species in tropical East Africa with this growth habit.