Costus phyllocephalus K.Schum.

Kamer 1, H. Maas-van de, Maas 1, P. J. M., Wieringa 1, J. J. & Specht, C. D., 2016, Monograph of African Costaceae, Blumea 61 (3), pp. 280-318 : 309-310

21. Costus phyllocephalus K.Schum. — Plate 3e ; Map 14

Costus phyllocephalus K.Schum. (1892) 420; (1904) 386. — Type: Von Mechow 508 (holo B destroyed; lecto Z, designated here; iso M), Angola, Prov. Malanje, Malanje (‘Malane’), Quango River , June–Aug. 1880 .

Costus nudicaulis Baker (1898) 300, syn. nov. — Type: Mann 1033 (holo K), Gabon, Estuaire, Gaboon River , July 1861 .

Costus dewevrei De Wild. & T.Durand in Durand & De Wildeman (1899) 139, syn. nov. — Type: Dewèvre 334 (holo BR; iso BR), Congo Kinshasa, Kinganga (‘Chinganga’), 29 Aug. 1895 .

Costus fissiligulatus Gagnep.(1902a) 93,syn. nov. — Type: A plant cultivated at Bot. Gard . Paris as ‘Gabon Nº 639’, July 1902 (holo P; iso P) .

Costus fissiligulatus Gagnep. var. major Gagnep. (1902a) 94, syn. nov. — Type: Griffon du Bellay s.n. (holo P), Gabon, without locality, ‘ Donné par l’Exposition Coloniale. Cat. 1864 Nº. 4 ’ .

Costus ubangiensis Gagnep. (1902a) 97, syn. nov. — Type: Viancin s.n. (holo P), Central African Republic, ‘ Haut-Oubangui’ .

Costus nudicaulis Baker var. pilosa Gagnep. (1902b) 19, syn. nov. — Type: Lecomte B25 (holo P), Congo Brazzaville, ‘Nounzi’, Oct. 1893 .

Costus violaceus Koechlin (1964) 88,pl. 20,syn.nov. — Type: N. Hallé 1543 (holo P), Gabon, Ogooué-Maritime, Port-Gentil , 2 Apr. 1959 .

Costus foliaceus Lock & A.D.Poulsen in Poulsen & Lock (1997) 614, f. 3, pl. 2a, syn. nov. — Type: Poulsen et al. 503 (holo K; iso C, ENT, MHU), Uganda, Bushenyi District, Kasyoha-Kitomi Forest Reserve, NE of Kyam- bura River, 1250 m, 4 June 1994 .

Costus sp. A Lock & Diniz (2010) 120.

Terrestrial herb 0.2–3 m tall. Leaves many; sheaths 0.5–2 cm diam; ligule brown, upper margin reddish, membranous, split into 2 very unequal obtuse to acute lobes, 10–50 mm long; petiole 3–10 mm long; sheaths, ligule and petiole sparsely to densely covered with erect, brown hairs to c. 3 mm long; lamina green to purple below, rarely red on both sides, narrowly ovate to narrowly obovate, 10–31 by 4–12 cm, upper side glabrous or rarely sparsely to densely covered with erect hairs to c. 3 mm long, lower side rather densely to sparsely covered with erect brown hairs to c. 3 mm long to glabrous, base obtuse, rarely subcordate, apex acuminate (acumen 15–25 mm long). Inflorescence (few- to) many-flowered, ovoid to globose, 2.5–10 by 3–7 cm, terminating the leafy shoot, sometimes sprouting from the axils of the lower bracts; bracts, appendages of bracts, bracteoles, calyx, ovary and capsule sparsely to densely cov- ered with erect hairs <1 mm long to glabrous. Flowers 1 per bract; bracts green to reddish purple, coriaceous, ovate-elliptic to broadly so, 1–2.5 by 1–2.5 cm, callus sometimes present and then 1–2 mm long; appendages mostly present, green, horizontally spreading to reflexed or rarely erect, narrowly tri- angular to rarely broadly ovate-triangular, 1–4.5(–6.5) by 5–20 cm; bracteole boat-shaped, 1(–2)-keeled, 11–21 mm long, cal- lus 2–3.5 mm long; calyx 10–27 mm long, lobes shallowly to broadly triangular, 2–4 mm long, callus absent; corolla white to pale pink to lilac, 40–65 mm long, glabrous, rarely covered with erect hairs <1 mm long, tube 10–20 mm long, lobes narrowly obovate to narrowly elliptic, 30–55 mm long; labellum white to pale pink on the outer side, inner side white with the upper half striped dark pink to lilac to dark purplish pink, or completely white to very pale pink, with yellow nectar guide, horizontally flattened, broadly obovate when spread out, 40–70 by 50–70 mm, fimbriate, margin crenulate and/or undulate, sometimes 5-lobed; stamen white to yellow or dark pink, 30–45 by 10–15 mm, apex yellow, tip of apex pink or pale yellow, toothed, anther 7–9 mm long. Capsule subglobose to obovoid, 6–15 by 6–15 mm. Seeds 2–3 by 1–1.5 mm.

Distribution — West Africa (Nigeria); Central Africa (Burundi, Cameroon, Central African Republic, Congo Brazzaville, Congo Kinshasa, Gabon); East Africa (Uganda); Southern Tropical Africa (Angola, Zambia).

Habitat & Ecology — In primary or secondary rainforest, gallery forest, sometimes in coastal forest or in wet places near savannas, rivers or creeks, or along roads, at elevations of 0–1500 m. Flowering and fruiting: all year through.

Field observations — On the label of the specimen Le Testu 2374 is written ‘fleurs très odorantes’.

IUCN Conservation Status — Least Concern.

Notes — Costus phyllocephalus can be recognized by a combination of green appendaged bracts, leaves on flowering shoot concentrated just below the inflorescence, flowers of which the horizontally flattened labellum is whitish pink to striped with dark purplish pink and a long brown membranous ligule (10–50 mm long). The upper brown membranous part of this ligule can be deciduous only leaving the lower green tubular part. Costus phyllocephalus looks quite similar to C. ligularis . For the differences between both species see under the latter. In C. phyllocephalus young shoots are sometimes formed from the lower bracts; these shoots have relative small ligules. In the fruiting stage the calyx is often protruding beyond the bracts. Some collections are aberrant from typical C. phyllocephalus in having unappendaged bracts. Sometimes there are transitions between the uppermost leaves and the appendages of the lowest bracts. The shoots are reddish and the leaves tend to be concentrated at the top of the shoot. The yellow central blotch (nectar guide) is situated in the throat of the flower and does not reach the outer margin of the labellum as in C. lucanusianus .

Figures

Plate 3 a. Costus kupensis Maas & H.Maas. Basal inflorescence. – b. Costus lateriflorus Baker. Habit showing lateral inflorescences. – c. Costus tappenbeckianus J.Braun & K.Schum. Inflorescence with flower. – d. Costus lilaceus Maas & H.Maas. Lateral inflorescence. – e. Costus phyllocephalus K.Schum. Inflorescence. – f. Costus maboumiensis Pellegr. Inflorescence (a: Maas et al. 10575; b: photographed in Lyon Arboretum Hawaï, no specimen collected; c: Burgers’ Bush number 20140016; d: photographed in Burgers’ Bush, Arnhem, The Netherlands, no specimen collected; e: Maas et al. 10407; f: Maas et al. 10227). — Photos: a, c–f: P.J.M.Maas; b: J.Mood.

Map 14 Distribution of Costus phyllocephalus K.Schum.