Prota 3: Dyes and tannins/Colorants et tanins
Prodr. fl. nepal.: 91 (1825).
Scrophulariaceae (APG: Orobanchaceae)
n = 14
Buchnera longifolia Klotzsch (1861).
Origin and geographic distribution
Buchnera hispida is widespread in tropical Africa and subtropical southern Africa, Madagascar and Comoros, and through Yemen and Oman to India.
The whole plant of Buchnera hispida turns blue-black if bruised and becomes black after drying. The dried powdered plant is used as source of a black dye for skin and textiles in Gambia. In Tanzania dried powder is mixed with castor oil and applied externally to treat scabies and eczema.
No information on the phytochemistry of Buchnera hispida appears to be available, but several Buchnera species contain iridoids which, if also present in Buchnera hispida, could contribute to its colouring action.
Facultative hemiparasitic, erect annual herb up to 1 m tall with simple or branched, hairy or scabrid stem. Leaves in a rosette at base in young plants, alternate on the stem, simple, sessile, rigid-hairy to scabrid; stipules absent; rosette leaves elliptical to almost circular, 2–3.5 cm × 1.5–2 cm, margin entire, 3-veined with a pinnately divided midrib; lower stem leaves ovate-lanceolate to oblong, 4.5–7.5 cm × 1–2.5 cm, margin entire to coarsely irregularly toothed, 3-veined with midrib pinnately divided; upper stem leaves linear-lanceolate, 1.5–4 cm × 1–2.5 mm, margin entire to remotely dentate, 1-veined. Inflorescence a terminal lax spike up to 25 (–40) cm long; bracts leaf-like. Flowers bisexual, regular, 5-merous, nearly sessile; calyx tubular, 4–8 mm long, 10-veined, rigid-hairy, lobes 1–2 mm long; corolla tubular, tube cylindrical, up to 7.5 mm long, hairy, lobes equal, blue, purple or white, throat villous; stamens 4, inserted on corolla tube, included, 2 slightly longer than other 2; ovary superior, 2-celled, style filiform, stigma club-shaped to cylindrical. Fruit an ovoid capsule up to 5.5 mm × 3 mm, many-seeded. Seeds longitudinally striate.
Buchnera comprises about 100 species and occurs mainly in the tropics of the Old World, with about 90 species in tropical Africa. It is closely related to Striga, which comprises parasitic plants that are more destructive to crops.
Buchnera leptostachya Benth. is also used as a dye in Gambia, and as an ear medicine in Tanzania. It is an annual or perennial, almost glabrous herb up to 50 cm tall, with pink, blue or white flowers slightly smaller than those of Buchnera hispida, and it is found throughout tropical Africa, often in wet grasslands and coastal bushland, often on saline soils.
Buchnera hispida is a facultative hemiparasite; when no host plant is available it can flower and fruit independently, but with a host its growth is better. It requires light for germination. Although dark incubation in water before illumination is not absolutely necessary for germination, in tests it caused the seeds to respond more rapidly to light. The longer the time of the dark incubation the more responsive the seeds were to light.
Buchnera hispida is a weed of cultivated land which can parasitize roots particularly of cereal crops, e.g. sorghum, millet and maize, but is hardly ever a serious noxious weed. It is also found in well-drained grassland on sandy soils, often in open woodland, from sea-level up to 1800 m altitude.
Genetic resources and breeding
Buchnera hispida is widespread and not in danger of genetic erosion.
Buchnera hispida as a source of dye will remain only very locally of some importance. Its medicinal properties need further investigation for evaluation.
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• Nwoke, F.I.O. & Okonkwo, S.N.C., 1980. Photocontrol of seed germination in the hemiparasite Buchnera hispida (Scrophulariaceae) (dark incubation, light, facultative root parasite of grasses). Physiologia Plantarum (Denmark) 49(4): 388–392.
• Okonkwo, S.N.C. & Nwoke, F.I.O., 1974. Seed germination in Buchnera hispida Buch.-Ham. ex D. Don. Annals of Botany 38: 409–417.
• Wongsatit Chuakul, Noppamas Soonthornchareonnon & Orawan Ruangsomboon, 2003. Buchnera L. In: Lemmens, R.H.M.J. & Bunyapraphatsara, N. (Editors). Plant Resources of South-East Asia No 12(3). Medicinal and poisonous plants 3. Backhuys Publishers, Leiden, Netherlands. pp. 96–97.
Correct citation of this article:
Jansen, P.C.M., 2005. Buchnera hispida Buch.-Ham. ex D.Don In: Jansen, P.C.M. & Cardon, D. (Editors). PROTA 3: Dyes and tannins/Colorants et tanins. [CD-Rom]. PROTA, Wageningen, Netherlands.