Cassia abbreviata subsp. beareana pods

Here is a Cassia abbreviata subsp. beareana, long-tail cassia tree, early in May in the Kruger National Park with hardly a leaf left from its southern hemisphere summer season.

The long pods, the tails of the common name, persist through winter. The next event for this tree comes in spring when masses of yellow flowers suddenly arrive to brighten the neighbourhood before the new leaves sprout.

Although the Lowveld is not that cold in winter, most of the indigenous trees here are winter deciduous. There are also summer deciduous plants that hide from heat by resting or capitalise on winter rainfall. During this dormant, dry and leafless phase, the rest period for the trees and grass, the browsers of leaves (and even some grazers of grass) are adapted through learning to eat something else as best they can.

Each species finds solutions for given foodstuffs running out seasonally. The learning is embedded in the collective memory of the whole species (or just the regional tribe), gained over thousands of previous winters or other seasonal shortage cycles.

Searching by herbivores is thus in a way similar to hunting by carnivores. Survival skills include collective memory of areas where certain dietary components can be found when specific weather conditions arrive. Still, some animals will get thin; even starve in the off-season, especially the grass-dependent species (Coates Palgrave, 2002).