Drosera elongata Exell & J.R.Laundon

Rjosk, A., Neinhuis, C., Monizi, M. & Lautenschläger, T., 2022, Synopsis of the genus Drosera (Droseraceae) in Angola and the Democratic Republic of the Congo, Blumea - Biodiversity, Evolution and Biogeography of Plants 67 (1), pp. 1-14 : 7

4. Drosera elongata Exell & J.R.Laundon — Fig. 6

Drosera elongata Exell & J.R.Laundon (1955b) 42; J.R. Laundon (1970) 29; A.S.Rob. et al. (2017) 1384. —

Type: A.W. Exell & F.A. Mendon ҫa 1268 (holo BM), Angola, Lunda Sul, Luma-Cassai , ‘Tenga’, 27 Apr. 1937 .

Slender, scrambling, caulescent herb. Stems up to 90 cm long, c. 1 mm diam, flexuous, pilose to densely pilose ( Fig. 6b ). Leaves evenly spaced along the stem, alternate to spirally arranged, semi-erect, older leaves perpendicular to stem or slightly reflexed; stipules 2–5 mm long, membranous, deeply lacer- ated apically, ferrugineous; lamina obovate to elliptic, 3–6 by 2–4 mm, bearing tentacles adaxially and around the margins, pilose abaxially ( Fig. 6a ); petiole 0.7–1.5 cm long, slender, pilose. Inflorescences cymose, with 2–9 flowers; peduncles 1 or 2 together, 9–25 cm long, arising laterally, ascending, pilose to glandular-pilose; bracts linear to oblanceolate, 2–3 mm long, pilose or glandular-pilose; pedicels 1–6 mm long, pilose to glandular-pilose. Sepals 5, lanceolate to elliptic, 3–5 by 1–2 mm, connate at the base, apex obtuse or acute, glan- dular-pilose. Petals 5, obovate, 4–6 by 2–3 mm, obtuse, pink. Stamens 5, filaments 2–4 mm long. Pollen in tetrads, tetrads c. 45–50 µm diam, single grains c. 30 µm diam, echinate ( Fig. 6e ), echini conical, c. 2 mm long, sometimes constricted in the middle, in low to medium density, with short gemmate to clavate sculptural elements between echini. Pistil: ovary c. 1 by 1.5 mm, glabrous; styles 3, 2-partite at the base. Seeds fusiform, 0.5–0.8 by c. 0.2 mm, black, testa smooth ( Fig. 6f ).

Distribution — Angola, Burundi, Congo, DRC, Tanzania, Zambia ( Fig. 6c ).

Habitat & Ecology — Perennially wet places in seasonally dry wet-savannah, upland plateaus.

Additional specimens (see Fig. 6d for province map). ANGOLA, Lunda, R. Lalege , 14 Aug. 1927, Carrisso & Mendon ҫa 245a ( COI) ; Uíge, Mucaba swampy area , S7°13' E15°5', alt. 1209 m, 23 Feb. 2017, T. Lautenschläger 2017-02-113 ( DR) . – DRC, Haut-Katanga, Parc National de l’Upemba , Kiluba , Luswahila , alt. 1880 m, 16 Jan. 1948, G.F. de Witte 03249 ( BR) ; Parc National de l’Upemba, Kaziba , alt. 1300 m, 18 Apr. 1949, G.F. de Witte 06261 ( BR) ; Haut-Katanga / Haut-Lomami, Parc National de l’Upemba , alt. 1680 m, 24 Aug. 1949, G.F. de Witte 07540 ( BR) .

Note — Hybridisation with D. madagascariensis has been observed, the hybrids show characteristics of both species ( Robinson et al. 2017).

Figures

Fig. 6 Drosera elongata Exell & J.R.Laundon. a. Leaf shape with a pilose petiole and a relatively small, elliptic lamina; b. general morphology: very long stems with horizontal leaves and laterally arising, pubescent inflorescences; c. distribution according to the literature; d. province map of Angola and DRC with localities of examined herbarium specimens; e. pollen in tetrads with echinate, conical sculpture elements in low to medium density; f. dry seed 450 × 140 µm. — Scale bars: a = 1 cm; b = 2 cm; e = 10 µm; f = 20 µm.