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Premna maxima T.C.E.Fr.

Protologue
Notizbl. Bot. Gart. Berlin-Dahlem 8: 700 (1924).
Family
Verbenaceae (APG: Lamiaceae)
Origin and geographic distribution
Premna maxima is endemic to Kenya, where it is confined to a few small localities near Meru and Marsabit.
Uses
The wood of Premna maxima is suitable for construction, poles and piles, light flooring, mine props, ship and boat building, furniture and cabinet work, joinery, toys and novelties, agricultural implements, boxes and crates, vats, turnery, draining boards, food containers, veneer and plywood. In Kenya the wood is used in carpentry and construction. It has also been used for flour mills, stave piping and cooling-tower slats.
Properties
The heartwood of Premna maxima is grey-brown or grey tinged with green, and not clearly demarcated from the sapwood. The grain is straight, texture medium and even. The density of the wood is 560–740 kg/m³ at 12% moisture content. The wood seasons well, but sharp moisture gradients may occur. The wood is hard and stable, but its strength is below average for its density. It works well with all tools, and paints, polishes and varnishes satisfactorily. The wood is durable due to the presence of oil. The sapwood is not susceptible to Lyctus borer attack.
Botany
Medium-sized tree up to 30(–40) m tall; bole up to 90 cm in diameter, generally fluted and bent or crooked; outer bark dark, rough, flaking vertically in small scales; branchlets first rusty brown hairy, but soon glabrous. Leaves opposite or in whorls of 3, simple and entire; petiole 3–8 cm long, rusty brown hairy; blade broadly ovate to elliptical or rounded, (6–)7–12(–19) cm × (4–)5–10.5(–16) cm, base usually rounded, apex rounded to acuminate, slightly yellowish hairy above, grey woolly hairy beneath, sometimes glabrous on both surfaces. Inflorescence a terminal umbel-like panicle, 12–16(–20) cm × 11–14 cm, yellow hairy, branches up to 6 cm long; bracts triangular, 5–9 mm × 1–4 mm. Flowers bisexual, zygomorphic; pedicel c. 1 mm long; calyx campanulate, c. 3.5 mm long, yellow hairy, 2-lipped, one lip 2-toothed, the other entire, persistent; corolla creamy white, narrowly funnel-shaped, tube c. 3 mm long, with 4 lobes, 2-lipped, lobes rounded and c. 2.5 mm × 2 mm; stamens 4, inserted in corolla tube, 2 longer and 2 shorter; ovary superior, 2-celled or falsely 4-celled, style subulate, c. 1.5 mm long, shortly 2-lobed at apex. Fruit a globose drupe c. 8 mm in diameter when dry, purplish; endocarp bony, few-seeded. Seeds oblong.
Premna comprises about 225 species, distributed mainly in the Old World tropics and subtropics.
In Kenya Premna maxima has been found flowering from January to June.
Ecology
Premna maxima occurs at 1150–1800 m altitude in moist evergreen forest.
Genetic resources and breeding
The distribution of Premna maxima is limited to a single country, and it is classified as vulnerable on the IUCN Red list of threatened species. The population in the Marsabit National Reserve in Kenya is protected, and Premna maxima is being propagated in the Plant Conservation Programme in Kenya.
Prospects
Premna maxima has a restricted distribution and is considered vulnerable; hence harvesting the timber from wild stands should be discouraged.
Major references
• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Verdcourt, B., 1992. Verbenaceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 155 pp.
Other references
• Battiscombe, E., 1936. Trees and shrubs of Kenya colony. Government Printer, Nairobi, Kenya. 201 pp.
• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
• Wimbush, S.H., 1957. Catalogue of Kenya timbers. 2nd reprint. Government Printer, Nairobi, Kenya. 74 pp.
• World Conservation Monitoring Centre, 1998. Premna maxima. In: IUCN. 2006 Red list of threatened species. [Internet] http://www.iucnredlist.org. Accessed February 2007.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Brink, M., 2007. Premna maxima T.C.E.Fr. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.