Costus lateriflorus Baker
Creators: name: Kamer 1, H. Maas-van de
name: Maas 1, P. J. M.
name: Wieringa 1, J. J.
name: Specht, C. D.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Zingiberales
Costaceae
Costus
Costus lateriflorus

description: <b> 12. <i>Costus lateriflorus</i> Baker</b> — Plate 3b; Map 8 <i>Costus lateriflorus</i> Baker (1898) 301; K.Schum. (1904) 413. — Type: <i>Mann 1629</i> (holo K; iso P), Equatorial Guinea, Litoral Prov., Corisco Bay, Mount John, River Kongui, Aug. 1862. <i>Costus letestui</i> Pellegr. (1929) 220 (as ‘ <i>Le Testui</i> ’), syn. nov. — Type: <i>Le Testu 1683</i> (holo P; iso BM, K), Gabon, Nyanga, Tchibanga area, Mayombe bayaka, Ighouma, 8 km NE from Mouila, 12 Jan. 1913. Epiphytic or sometimes terrestrial herb to c. 1.5 m tall. <i>Leaves</i> many; sheaths 0.4–0.7 cm diam; ligule reddish brown, mem- branous, truncate, 25–40 mm long, sometimes longer than the internode; petiole 4–10 mm long; sheaths, ligule and petiole glabrous; lamina sometimes purplish on lower side, coriaceous and somewhat fleshy, narrowly elliptic, 9–20 by 2–6.5 cm, glabrous on both sides, base acute to obtuse, apex acuminate (acumen 5–12 mm long). <i>Inflorescences</i> generally several per flowering branch, each one few- to several-flowered, ovoid, 2–4 by 1–3 cm, lateral in the axil of a leaf with a peduncle 1–4 cm long or terminating a separate leafless shoot c. 1 cm long or terminal on a leafy shoot; bracts, bracteoles, calyx, ovary and capsule rather densely to densely covered with erect hairs &lt;1 mm long, rarely glabrous. <i>Flowers</i> 1 per bract; bracts pale brownish green to reddish brown, slightly dotted with pink, chartaceous, ovate, 0.5–1 by 0.3–0.8 cm, callus sometimes present and then c. 1 mm long; appendages absent; bracteole tubular, 8–12 mm long, callus sometimes present and then c. 1 mm long; calyx pale pinkish green to reddish brown with pale green lobes, 12–18 mm long, lobes shallowly ovatetriangular, 1–2 mm long, callus distinct, green, 1–2 mm long; corolla hyaline, whitish with some pink or brown and red dots, 35–50 mm long, glabrous, tube 15–20 mm long, lobes narrowly elliptic-ovate, 20–35 mm long; labellum at the inner and outer side bright yellow, horizontally flattened with funnel-shaped base, broadly obovate when spread out, 40–60 by 35–60 mm, margin crenulate; stamen white with red dots, 20–27 by 8–11 mm, apex yellow, anther 7–10 mm long. <i>Capsule</i> ellipsoid, c. 12 by 6 mm. <i>Seeds</i> c. 1.5 by 1 mm. Distribution — West Africa (Nigeria); Central Africa (Cam- eroon, Central African Republic, Equatorial Guinea, Gabon). Habitat &amp; Ecology — In primary or sometimes secondary rainforest rich in <i>Caesalpinioideae</i> and <i>Sacoglottis gabonensis</i>, sometimes epiphytic on <i>Baillonella toxisperma</i> and <i>Tetraberlinia bifoliolata</i>, or on sandy to rocky soil, at elevations of 0– 800 m. Flowering and fruiting: all year through. IUCN Conservation Status — <i>Costus lateriflorus</i> occurs in about 17 locations with an AOO of 104 km 2. Six of these loca- tions have a protected status. Since we are unable to identify material of this species or <i>C. lilaceus</i> where the petal colour is not apparent, this species is likely to be more common than currently assessed. We therefore assess it as Least Concern (LC). Notes — <i>Costus lateriflorus</i> can be recognized by its mostly epiphytic habit, flowers with a bright yellow labellum and its inflorescences placed laterally in the axil of a leaf or terminating a separate leafless shoot. However, it is almost impossible to distinguish <i>C. lateriflorus</i> from <i>C. lilaceus</i> except for the strik- ing difference they show in the colour of their labellum: yellow in <i>C. lateriflorus</i> and lilac in <i>C. lilaceus.</i> In the material studied we found 12 specimens to be unidentifiable due to lack of information regarding flower colour on the label. The shoot of <i>C. lateriflorus</i> is brown (ligule) alternating with green (internodal part of the stem). The labellum of the flowers of <i>C. letestui</i> Pellegr., now in syn- onymy with <i>C. lateriflorus</i>, was described by Koechlin (1965, 1965) as being pink. However, the flowers of <i>C. letestui</i> are yellow, as in <i>C. lateriflorus</i> Baker, because the label of the type specimen <i>Le Testu 1683</i> (P) reads: ‘Epiphyte à fleurs jaunes’.
description: Published as part of <i>Kamer 1, H. Maas-van de, Maas 1, P. J. M., Wieringa 1, J. J. &amp; Specht, C. D., 2016, Monograph of African Costaceae, pp. 280-318 in Blumea 61 (3)</i> on pages 300-301, DOI: 10.3767/000651916X694445, http://zenodo.org/record/7570023