Drosera, Linnaeus, 1753

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 : 3-4

Drosera L. — Fig. 2

Drosera L. (1753) 281; Keay (1954) 120; Oberm. (1970) 189; J.R. Laundon (1978) 64; Kubitzki & C.Bayer (2003) 201; A.M. Ellison & Adamec (2018) 50. —

Type: D. rotundifolia L.

Carnivorous, annual or perennial herbs. Stems caulescent or acaulescent. Leaves simple, in a basal rosette or alternate to spirally arranged along the stem; stipules present or absent, membranous, often lacerated; petiole present or confluent with lamina; lamina variously shaped ( Fig. 2 ), adaxial surface covered with short- and long-stalked glands (tentacles) and digestive glands that trap and digest insects. Inflorescences 1–many-flowered cymes, axillary or terminal, flowers bisexual. Sepals 5 (rarely 4–8); ± connate at the base. Petals 5 (rarely 4–8); free. Stamens 5 (rarely 4–8); free. Pollen in tetrads. Pistil: ovary (2–)3–5 carpels; styles (2–)3–5. Fruit a loculocidal capsule. Seeds small, numerous.

Distribution — Over 240 species, almost worldwide.

Habitat & Ecology — Swamps, sandy, seasonally and peren- nially wet and low-nutrient habitats.

KEY TO THE ANGOLAN AND CONGOLESE DROSERA SPECIES

1. Stipules absent, lamina linear............. 6. D. indica

1. Stipules present, lamina lanceolate, spathulate, obovate, ovate, elliptic, suborbicular or orbicular.............. 2

2. Acaulescent, leaves in a basal rosette, leaves horizontal. 3

2. Caulescent, including short stems (one to several cm long, rarely appearing acaulescent), young leaves erect, older leaves variable (erect, perpendicular to stem, reflexed).. 5

3. Seeds fusiform, seed testa reticulate, peduncle strongly curved at the base, peduncle, pedicels and sepals glabrous, glandular or pilose, petals pink or purple. — Usually caules- cent, rarely dwarf forms with suppressed stems................................... 8. D. madagascariensis

3. Seeds ovoid, seed testa smooth or reticulate, peduncle curved at the base, peduncle, pedicels and sepals glandular or pilose, petals pink to purple or white.............. 4

4. Petiole narrow, abruptly broadening into the suborbicular to spathulate lamina, peduncle, pedicels and sepals glandular, petals white or purple, seed testa reticulate 3. D. burkeana

4. Petiole gradually broadening into the elliptic to obovate lamina, peduncle, pedicels and sepals usually pilose, petals pink to purple, seed testa smooth.......... 9. D. pilosa

5. Peduncle arising apically, erect throughout its whole length, stem very short (c. 4 cm long), densely pilose, seeds sub- orbicular to ovoid.................... 2. D. bequaertii

5. Peduncle arising laterally, curved or erect at the base, then ascending, stem short to very long (up to 90 cm), glabrous, glandular or pilose, seeds fusiform................. 6

6. Older (but still green) leaves reflexed towards the stem, old parts of the stem enclosed with old reflexed leaves, peduncle strongly curved at the base..... 8. D. madagascariensis

6. Older (but still green) leaves held erect or ± perpendicular to the stem (rarely reflexed), peduncle ± curved at the base 7

7. Stem up to 90 cm long, older (but still green) leaves per- pendicular to stem, lamina obovate to elliptic, peduncle and petioles pilose or glandular-pilose........ 4. D. elongata

7. Stem shorter (max. 25 cm long, sometimes longer), older (but still green) leaves ± erect, lamina ± spathulate, peduncles and petioles glabrous/sparsely pilose or densely pilose. 8

8. Peduncle and petioles densely pilose/hirsute, stem up to 15 cm long, densely glandular, lamina oblong-spathulate. ― Only known from Katanga, DRC.... 7. D. katangensis

8. Peduncle and petioles glabrous or sparsely pilose, stem short (up to 10 cm) or elongated (up to 25 cm), glabrous, lamina narrowly spathulate, spathulate or obovate..... 9

9. Stem short (up to 10 cm), leaves closely arranged, petioles very slender and 3–7 cm long............. 1. D. affinis

9. Stem elongated (up to 25 cm, sometimes longer), alternating between segments with evenly spaced leaves and segments with rosette-like clustered leaves, petioles max. 3.2 cm long.............................. 5. D. flexicaulis

Figures

Fig. 2 Leaf shapes of Angolan and Congolese Drosera L. species. The leaf shapes of Drosera vary in lamina form, lamina size, petiole length and petiole hairiness. — Scale bar = 1 cm.