Can't comment on the Masai use of woods as I've only been in Kikuyu land when I've been in Kenya. With regard to the San Bushmen, and the other bushman tribes they can make a fire with just about any piece of wood. They do obviously have their preferences if given a choice of woods.
There is an old story about how the !Kung bushmen got their fire;
Long time ago there was a time when there was no fire on earth and all people ate their food raw. One man, /Ka/Kani, discovered the art of making fire by twirling one stick on another, and so he and his family ate cooked food. However, they did not share their knowledge with other people - until a chance visit by Gao!na, when /Ka/Kani was not home, left them no choice in the matter. Gao!na asked /Ka/Kani's children for something to eat, and they gave him cooked food. It was so delicious that he came back the next day for more, and as he approached he saw /Ka/Kani making fire with his sticks, so he watched from a distance to see how it was done and how food was cooked. After noting where /Ka/Kani hid his firesticks Gao!na went into his camp as if he had seen nothing, and joined in the meal. But his chief interest was not to lay hands on the firesticks, and so, after they had eaten, he suggested that they play a game with the djanis (see below). He then made two djanis with guinea fowl feathers and sticks. However, /Ka/Kani's djani did not fly high enough or drift far enough to draw him away from the place where he had hid the firesticks. So Gao!na replaced the feathers with bustard feathers, and the next time /Ka/Kani threw his djani it flew higher and took longer to come down. Gao!na then caused a wind to blow the djani so that /Ka/Kani had to run a long way past him while chasing after it. Seeing his chance, Gao!na then immediately dashed to the hiding place, and taking hold of the firesticks, broke them into small pieces and threw them into the air, spreading them over the whole world. As punishment for his selfishness /Ka/Kani was changed into a bird, and since then the people everywhere have cooked their food, and from that day there has been a fire lurking in every piece of wood.
A djani is a game common among bushman and black african children in the Kalahari region of Southern Africa. It is a childs toy consisting of a 30 cm long hollow reed with soft underfeathers of (usually) guinea fowl stuck into one end, and a short thong weighted with a nut or lump of gum in the other end tied on with sinew. A large feather is tied on to the reed about midpoint to give the toy its spin when hurled into the air. The game is played so that each contestant have a stick (50-80 cm length) with which the djani is caught and hurled up into the air. The idea of the game is to keep the djani in the air for as long as possible. If one fails to catch and hurl the djani up with the stick, he out of the game. The game is finished when there is only one contestant left.