Croton megalocarpus Hutchinson

Croton megalocarpus grows to 15-35 m; it has distinctive layering of branches and a rather flat crown. Bark dark grey, rough, and crackling. Hardy and fast growing. Leaves variable, long, oval and pointed to about 12 cm. The dull green upper surface contrasts with the pale, silvery underside. Flowers conspicuous but very short-lived; yellow white, inserted in many-flowered, silver-budded racemes, up to 30 cm long; a few female flowers towards the base, the remainder male. Fruit turns from green to greyish-brown as it matures. Endocarp hard and woody. Each fruit contains 3 ellipsoid-ovoid or oblong-ellipsoid seeds, 2.2-2.4 cm long and 1.2-1.4 cm wide. Seeds white when immature, grey-brown when mature, with a minute caruncle. The generic name ‘Croton’ is based on the Greek word for ‘tick’, because of the appearance of the seed. The specific epithet means large-fruited.

After pollination by insects, fruit development takes 5 months and mature fruits can be collected from the ground. In Kenya, seeds mature during October-November in central regions, and from January to March in western regions. C. megalocarpus is monoecious, occasionally dioecious.

C. megalocarpus is a pioneer species and it is found growing in cleared parts of natural forests, forest margins or as a canopy tree.

Direct sowing is a viable propagation method. Seeds are extracted by cracking the shell with a hammer or stone, then they are sun-dried to 5-9% mc. Presowing treatment is not necessary. Under ideal conditions, the seeds germinate within 35-45 days, with an expected germination rate of 95% for mature and healthy seed lots. Vegetative propagation can be done by grafting or cuttings.

The species regenerates well through seedlings, and under favourable climatic conditions may sometimes become invasive. Young trees coppice well after pruning, but fruiting is unlikely with intensive pruning, such as in hedgerow management. In agroforestry systems, it is sometimes managed as scattered trees in farmland because of its open canopy and usefulness for mulching.

The tree is reported have been damaged by Ambrosia beetles in areas between 1300 to 2100 m in Kenya. Other insect pests recorded include Scolytidae.

The seeds are extracted from the shell by cracking with a hammer or a stone. On average there are 1700 seeds/kg. The seeds are dried in the sun to approximately 5-9% moisture content and thereafter can be stored up to 1 year at 3°C. After sowing, the seeds germinate within 35-45 days, attaining germination rates of 95% without any pretreatment.

Shade or shelter: C. megalocarpus forms a flat crown and has horizontal layers of branches, which make it useful in providing light shade and serving as a windbreak. Soil improver: Leaves have high levels of nitrogen and phosphorus and serve as a source of mulch, for instance, in coffee plantations. Ornamental: Its conspicuous flowers make it suitable as an ornamental. Boundary or barrier or support: As the species is not browsed by livestock, it is often used as a live hedge.

Fodder: The seed is incorporated in poultry feeds, as its protein content is high (50%). Fuel: Well-dried nuts are reportedly used in some areas together with charcoal in cooking stoves. The tree is also utilized for firewood. Apiculture: This species produces a dark-ambered honey with strong flavour. Timber: Wood is of medium weight, hard, termite-resistant, strong; it is used for timber and building poles. Medicine: Seed contains up to 32% oils, which have been used favourably as medicine. Bark decoction is used as a remedy for worms and whooping cough.