Why are spines of African Acacia species white?

Abstract

The straight white spines of African Acacia species are conspicuous, rather than being brown and cryptic as in other species. In comparison with species with brown spines, Acacia spines are composed of less dense material. I suggest that by the Acacia spines being readily apparent, browsers can avoid biting them. This avoidance facilitates the trade-off of decreased sturdiness for increased apparency.