Many visitors to Kirstenbosch, particularly children, remember the huge tree on the main lawn whose crown reaches down to the ground and creates a magical private sanctuary for anyone who steps inside. Walk past it on just about any day and it will
Many visitors to Kirstenbosch, particularly children, remember the huge tree on the main lawn whose crown reaches down to the ground and creates a magical private sanctuary for anyone who steps inside. Walk past it on just about any day and it will be alive with the chatter of kids playing inside. This tree is a Breede River yellowwood, nearly as old as the Garden itself. It was planted as one of a pair, but the other one, equal in magnificence, was unfortunately blown down during a severe winter storm in May 1984.
Unlike the other yellowwoods that are tall trees with long straight boles, Breede River yellowwoods are usually multi-stemmed and as broad as they are high. It is the smallest of the South African yellowwoods, commonly reaching no more than 6 m in height, although trees in sheltered, well-watered ravines can reach 20 m. It is most often found growing in open, dry and exposed positions where it develops into a large gnarled bush or spreading shrub, or a small rounded tree.
The bark is smooth, grey to brown, sometimes peeling longitudinally in long narrow strips. Leaves are narrowly oblong-elliptic, usually 30 - 60 mm long and 3 - 5 mm broad, tapering to both apex and base, tough and leathery. They are spirally arranged and are usually crowded towards the ends of the shoots. Juvenile trees may have larger leaves. The foliage is blue-green or grey-green; trees from Clanwilliam and Ceres districts generally have more silvery-grey leaves than those from the Swellendam and Robertson districts. At Kirstenbosch many of the specimens that are in the garden were selected for their glaucous foliage (i.e. the greyish-blue bloom on the leaves).
Yellowwoods are dioecious, i.e. there are male trees and female trees. Male cones are about 25 x 3 mm, cream to pinkish when fresh and are solitary or in groups of 2 - 5 in leaf axils. They are made up of many spirally arranged scales, each scale bearing two pollen sacs on its lower surface. The female cones are solitary, also borne in the leaf axils, on a naked (i.e. it bears no leaves or scales) stalk 4-6 mm long. The female cone is reduced to 1 or 2 fertile scales, each bearing 1 seed, that sit on top of a conical fleshy receptacle 9-15 x 10-16 mm that is actually a few sterile scales that have fused with each other and with the cone axis The receptacle is glaucous green turning to bright scarlet when the seed is ripe ageing to almost black. The seeds are smallish dark blue-green to dark violet berries with a leathery shell, 7-10 mm in diameter. The seeds mature rapidly and are on the trees in late summer to autumn (from January to May). The seed does not remain viable for long and should to be sown soon after it is ripe. Germinated seedlings have 2 cotyledons.
This species is closely related and very similar to Podocarpus latifolius, the true yellowwood, and they are often difficult to identify where their ranges overlap. A way to distinguish them is to look for the scattered stomata (pores) on the upper surface of P. elongatus leaves - you will find them in longitudinal grooves on the upper surface of most leaves. The grooves are usually near the margin or the petiole and are visible to the naked eye but you will need 10x lens to see the stomata. Both species have stomata on the lower surface of the leaves, but on Podocarpus latifolius they are very few to none on the upper surfaces. In general, the leaves of Podocarpus elongatus tend to be narrower and shorter, and more greyish to bluish and less shiny than Podocarpus latifolius. Also Podocarpus latifolius male cones are not found in groups but only singly or in pairs.
Podocarpus elongatus is wind pollinated. It may be a primitive method, but is far from ineffective or random. A recent study shows that female P. elongatus ovules selectively extract P. elongatus pollen from the air; even though the air contains pollen from other species 98.9% of the sampled ovules contained only P. elongatus pollen. The foreign particles in 1.1% of the ovules were particles of black carbon and tiny grains of sand - no foreign pollen grains were found. Furthermore, one of the tree being studied was isolated and quite far from any male trees yet the ovules were pollinated.
The seeds are eaten and dispersed by small mammals and birds that relish the juicy brightly coloured receptacles. The leaves show adaptations to surviving in a dry environment - they have a thick cuticle, a layer of wax covering the leaves, resin canals, sunken stomata and conspicuous supporting tissue.
P. elongatus has adapted to growing beside rivers and streams which are notoriously unstable - riverside plants are often partially up-rooted, knocked over or damaged by floods or rocks carried in the water, 