Nick Garbutt / Masai Giraffes (Giraffa camelopardalis) on open plains browsing Whistling Thorn Acacia (Acacia drepanolobium). Slopes of the Ngorongoro Highlands with the Serengeti Plains beyond, Tanzania. (Digitally...

Gerry Ellis / Whistling Thorn (Acacia drepanolobium) tree over savannah, Masai Mara National Reserve, Kenya

Mitsuaki Iwago / Masai Giraffe (Giraffa tippelskirchi) feeding on Whistling Thorn (Acacia drepanolobium) acacia tree, Serengeti National Park, Tanzania

Gerry Ellis / Whistling Thorn (Acacia drepanolobium) and moon, Amboseli National Park, Kenya

Mitsuaki Iwago / Whistling Thorn (Acacia drepanolobium) tree on savannah at sunset, Serengeti

Shin Yoshino / Whistling Thorn (Acacia drepanolobium) trees, Masai Mara National Reserve, Kenya

Mark Moffett / Ant (Pseudomyrmex sp) group drink nectar from Whistling Thorn (Acacia drepanolobium) acacia tree and protect the tree from leaf eating enemies ensuring mutual survival, Costa Rica

Mark Moffett / Ant (Pseudomyrmex sp) gathers carrot-like growths from Whistling Thorn (Acacia drepanolobium) acacia tree for delivery to larva in nest, in return for baby food, ant protects Acacia, Costa Rica

Mark Moffett / Ant (Pseudomyrmex sp) gathers carrot-like growths from Whistling Thorn (Acacia drepanolobium) acacia for delivery to larva in nest, in return for baby food Ant protects Acacia, Costa Rica

Tui De Roy / Rufous-tailed Rock-Thrush (Monticola saxatilis) on Whistling Thorn (Acacia drepanolobium), Laikipia, Kenya

Gerry Ellis / Reticulated Giraffe (Giraffa reticulata) browsing on Acacia (Acacia drepanolobium) trees, Lewa Wildlife Conservancy, Kenya

Mitsuaki Iwago / Giraffe (Giraffa sp) mother and young browsing on Whistling Thorn (Acacia drepanolobium) acacia tree, native to Africa