Impatiens urundiensis Gilg

Fischer, Eberhard, Abrahamczyk, Stefan, Holstein, Norbert & Janssens, Steven B., 2021, Evolution of Impatiens (Balsaminaceae) in the Albertine Rift – The endemic Impatiens purpureoviolacea complex consists of ten species, TAXON 70 (6), pp. 1273-1299 : 1286-1288

Impatiens urundiensis Gilg in Bot. Jahrb. Syst. 51: 227. 1914 –

Holotype: Burundi. Reise nach Urundi u. Ruanda, Nordost-Urundi , Nord-Uha , Sommer 1911, H. Meyer 1082 (B barcode B 10 0153419 !).

Description. – Plants densely covered with brownish hairs, stem erect, up to 60–95 (120) cm tall. Leaves with petiole 9–17 mm long, with 0–3 pairs of extrafloral nectaries, lamina 45–99 × 25–46 mm, margin with 10–16 pairs of extrafloral nectaries. Inflorescence with 6–8 flowers, peduncle (4.5) 11.5– 28 mm long, pedicel 11–33.5 mm long. Flowers large, pink, petal base barely yellow, purple maculae at base small, ± hidden in throat. Lateral sepals 7.5–11.5 × 1.5–3 mm. Lower sepal navicular, 12–19 mm long, 5–8 mm deep, abruptly constricted into a spiraled, usually filiform spur, spur 17–31.5 mm long. Dorsal petal 14–25 × 20–29 mm. Lateral united petals up to 40 mm long, upper lateral petal 18.5–24.5 × 11–15.5 mm, purple maculae on upper lateral petals small, spot-like, lower lateral petal 25.5–35 × 11.5–17 mm. Ovary beige to brownish pubescent, 4–5 mm long, ovary and fruits with brownish hairs. Fruit beige to brownish pubescent, up to 22–24 × 6–8 mm. Figures 2 , 4E,F , 10 , 11J–N .

Ecology. – Gallery forest in grassland, grassland with Exotheca and Eragrostis along rivers, and understorey of gallery forest, 1750–2000 m.

Distribution. – Burundi: Bururi-Kumuyange.

Specimens examined. – Burundi. Lacs Edouard et Kivu. Prov. Bururi, Munini, rives de la Siguvaye, 1900 m, S04°00′ E29°44′, 5 Mar 1980, Reekmans 8663 (BR) ; Bururi, Muyange, bord de Sikuyaye, 2000 m, 29 Jun 1971, Reekmans 1036 (BR); Bururi, Kwitaba, S04°05′ E29°48′, 1750 m, 12 May 1977, Reekmans 6207 (BR) ; Kumuyange, gallery forest near hot springs, gallery forest in montane grassland, 2000 m, 7 Oct 2013, E. Fischer 13301 (KOBL) .

Notes. – Impatiens urundiensis belongs to the group with hairy ovary. It is a very distinctive species with the plants densely covered with brownish hairs, the stems erect, up to 60–95 (120) cm tall, the flowers large, upper lateral petal 18.5–24.5 × 11–15.5 mm, purple maculae on upper lateral petals small, spot-like, ovary and fruits with brownish hairs. In contrast to all other species that occur in submontane to montane rainforest, it is confined to gallery forests in grassland. The petals display a sweet odour.

Figures

Fig. 2. Distribution map of the eight insect-pollinated species of the Impatiens purpureoviolacea complex. Dots indicate species with hairy ovaries, and stars mark species with glabrous ovaries.

Fig. 4. Seeds of the Impatiens purpureoviolacea complex. A & B, Impatiens purpureoviolacea: A, Seed; B, Detail of testa. C & D, Impatiens lutzmannii: C, Seed; D, Detail of testa. E & F, Impatiens urundiensis: E, Seed; F, Detail of testa. — Scale bars: A, 300 μm; B, 60 μm; C, 500 μm; D, 80 μm; E, 500 μm; F, 90 μm. A & B, Fischer 12958, BG Bonn 36240; C & D, Fischer 13002, BG Bonn 33486; E & F, Fischer 13301, BG Bonn 35170.

Fig. 10. Impatiens urundiensis. A, Detail of habit; B, Flower, lateral view; C, Flower, frontal view; D, Flower, dorsal view. — A–D, Fischer 13301, Burundi, Kumuyange.

Fig. 11. A–E, Impatiens purpureoviolacea. A, Flower; B, Lower sepal and spur; C, Dorsal petal; D & E, Lateral united petals. F–I, Impatiens lutzmannii. F, Flower; G, Lower sepal and spur; H, Dorsal petal; I, Lateral united petals. J–N, Impatiens urundiensis. J, Flower; K, Petiole, lateral sepals and anthers; L, Lower sepal and spur; M, Dorsal petal; N, Lateral united petals. — Scale bar: 1 cm. A–E, Fischer 13911, Rwanda, Rukarara; F–I, Fischer 13002, Burundi, Kumuyange; J–N, Fischer 13301, Burundi, Kumuyange.