Schotia brachypetala

Schotias often grow on termite mounds. The Schotia above-left (click to expand) is a healthy specimen in modest bushveld. Termites carry organic material back to their nests where it is broken down into nutrients like nitrogen, potassium and phosphorus, enriching the soil.

Termite mounds have well-aerated soil structures, creating healthy, slightly cooler micro-climates for roots. Mounds rise in height above-ground as termites excavate deep underground, carrying up different soil types that can be nourishing for trees.

Termites also clear some vegetation around their mounds, reducing competition for water and increasing water content in the soil.

Drainage lines give access to deep water during long dry winters. Above right is another robust Schotia on the banks of a drainage line.

Schotias have strong taproots that probe deep underground in search of water. Lateral roots also spread out, absorbing moisture and nutrients. Whether on termite mounds or drainage lines or rivers, Schotias access enough moisture to retain green foliage in the dry season.

Green in winter!

A lush green tree in mid-winter in Kruger Park may well be a Schotia brachypetala.

Schotias in the hot landscapes of Kruger are evergreen except for a brief phase in spring when trees drop their leaves as new leaves start appearing. In colder regions at higher altitudes, the trees are briefly deciduous.

The Schotia above left brags a full canopy of lush green foliage amidst a drab, dry winter landscape. The tree stands beside a termite mound and its tap root will be seeking moisture deep underground to support its foliage.

Diversity of landscapes is interesting. A Schotia, above right, germinated on the side of a rockface in the Nhlowa drainage that leads into the Sabie river, east of Lower Sabie. The tree's healthy, green condition in this mid-July scene shows the value of deeply-probing root systems.

Interestingly, the name of this spruit, Nhlowa, is the Tsonga name for the valley, and it means 'fresh, undiluted Marula juice', but we have not yet traced the origin of this curious association. Perhaps the pure, unpolluted water in the spruit aroused flavourful associations.

Bark of younger trees is smoother and lighter in colour than old trees, where bark becomes rough, cracked and grey, as in the image above right.

Crease lines often show in the bark of younger trees, above left, and that characteristic can be early supporting evidence of the identity of the tree.

The paripinnate leaves are alternate with 4 to 8 pairs of opposite to sub-opposite leaflets. Leaflet size is variable, but seldom larger than 80 by 40 mm. Leaflet size increases toward the leaf apex. Margins are entire, or slightly indented.

Newly emerging leaves come in beautiful shades of red, soon turning to fresh green, as in the image above.

As leaves mature, they darken in colour and leaflets become more leathery. Note in the image below that the rachis is narrowly winged.

Schotias advertise boldly for pollinators

Select bright crimson-red. Mass-produce flowers. Be lavish with nectar. Optimise visibility. Produce flowers in abundance before, or as new leaves emerge on the tree. All this creates impact!

Flowers are a distinctive feature of this species, and they are a magnet for all nectar-loving visitors, many of whom unwittingly pollinate the flowers.

Flowers are bisexual and presented in panicles, or dense branched heads on old wood. Flowering typically occurs from September to November.

Caution! Vehicles parked beneath flowering Schotias will soon be covered in sticky nectar!

Considering how are these flowers designed, and why are they designed this way, reveals some fascinating features.

The first curious feature is that petals not prominent. The 4 or 5 petals are short and broad, and may be reduced to linear filaments, or appear to be absent. The texture of petals is somewhat waxy and fleshy, designed to retain nectar and to withstand frequent visits by birds.

It is the bright red calyx that takes the lead in advertising. The 4 leathery sepals are fused at the base into a short calyx tube. The calyx encloses the flower bud before opening.

Numerous stamens are joined at the base and the crimson filaments extend well beyond the petals and sepals, each holding its anther that produces copious pollen.

Turning to the gynoecium, the single style extends a little beyond the stamens, holding the small stigma high and ready to accept pollen from arriving pollinators. This design promotes introduction of pollen from other flowers.

Interestingly, research has shown that there is a self‐incompatibility of the flower with its own pollen. The species thus depends on pollinators for fertilisation. (https://pmc.ncbi.nlm.nih.gov/articles/PMC10286656/#:~:text=brachypetala%20is%20pollinated%20almost%20exclusively,in%20terms%20of%20avian%20diversity.)

The superior ovary is formed from one carpel, and once fertilised, the ovary forms into a woody pod with a persistent style.

At the base of the ovary is a nectariferous disc that secretes abundant nectar. There is no need for the flowers to be strongly scented because the nectar, and the flower's bright red colour, are the magnet for pollinators.

Schotia brachypetala flowers are pollinated almost exclusively by birds. A diverse array of opportunistic avian nectarivores visit the flowers, from Weavers to White-eyes and Barbets to Bulbuls, together with many other species. The nectar is also a target for specialist nectarivores, such as sunbirds. Numerous bees, too, feed on nectar and collect pollen.

Schotia fruit is a hard, flattened, woody, brown pod with a hard margin.

Pods are typically about 6 to 10 cm long, tipped with a persistent style. They are dehiscent, taking several months to mature, turning from green to brown. They split open in late summer whilst still on the tree, releasing their seeds. 

Seeds are about 10 to 15 mm long, and generally oblong or ovoid in shape. They are edible, low in fat and protein and high in carbohydrates. Many indigenous peoples learned long ago to roast the seeds before eating them, and this practise is widespread today.

Note the conspicuous aril on the seeds above. Some bird species will eat the seeds and others will separate the sticky aril from the seed, eat the aril and drop the seed. That is a win for the bird. It is also an important win for the tree, which has allocated considerable resources to producing masses of nectar-laden flowers, all for the final purpose of distributing its seeds.

Schotias are a vital part of the spring to autumn feeding chain.

A wide array of bird and insect species feed on nectar while a tree is flowering, and insect-eating birds are drawn to the plethora of insects. Baboons, monkeys and squirrels eat both flowers and seeds.

Trees in a sub-region have uncoordinated flowering times, extending the nectar and seed-feeding season. This means that while one tree is in full flower, its neighbour a short distance away may have no flowers.

Why the 'Weeping' Boer-bean? In spring and early summer, as a tree is in full flower, excess nectar may drip to the ground, and imaginative minds likened this to tear drops dripping from the weeping tree.

A second source of drips may be the spittle bug, a small insect that parasitizes Schotias and other tree species (Ptyelus grossus). It sucks up sap and excretes a froth that collects and drips down the branches.

The species name brachypetala speaks to the flowers. 'Brachy' derives from the Greek word for short, and 'petala' refers to petals. Remarkably, in this flower design, the pink petals are slender, short or almost absent while the sepals are bright red and conspicuous.

The genus name Schotia honours Richard van der Schot, who ended his career as Director of the Menagerie at Schonbrunn Palace, which is now the Schonbrunn Zoo in Vienna. He lived from 1733 to1790.

Schotia heartwood is hard and termite resistant, with a dark walnut colour, and is used do make beautiful furniture and carvings. It is excellent, too, as firewood.