nother criterion often added to the definition

In places where the climate is suitable, trees are the climax vegetation[citation needed]. In some of the cool temperate regions, conifers tend to predominate, but in much of the southern hemisphere, the tropics, or in warm-temperate climates, broad-leaved trees are more common. Shade tolerance in young trees varies between species, and may determine the pattern of forest succession.
More than half the species of terrestrial plants and animals on the Earth are thought to live in tropical rainforests even though these occupy just five percent of the land area.[34] In tropical regions with a monsoon climate, where a drier part of the year alternates with a wet period, different species of broad-leaved trees dominate the forest, some of them being deciduous.[35]
Tropical regions with a drier savanna climate have insufficient rainfall to support dense forests[citation needed]; the canopy is not closed and plenty of sunshine reaches the ground which is covered with grass and scrub. Acacia and baobab are well adapted to living in such areas.[36]
In cool temperate parts of the world, particularly in the northern hemisphere, deciduous broad-leaved trees tend to be replaced by conifers. The long cold winter is unsuitable for plant growth and trees must grow rapidly in the short summer season when the temperature rises and the days are long. Light is very limited under their dense cover and there may be little plant life on the forest floor although fungi may abound.[37] Similar woodland is found on mountains where the altitude causes the average temperature to be lower thus reducing the length of the growing season
Although "tree" is a term of common parlance, there is no universally recognised precise definition what a tree is, neither botanically nor in common language.[3][4][5]
In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground.[6][7] Trees are also typically defined by height,[8][9][10] with smaller plants being classified as shrubs,[11] however the minimum height which defines a tree varies widely, from 10 m to 0.5 m.[10] By these broadest definitions, large herbaceous plants such as papaya and bananas are trees, despite not being considered as trees under more rigorous definitions.[3][5][12][13][14][15]
Another criterion often added to the definition of a tree is that it has a woody trunk.[10][16][17] Such a definition excludes herbaceous trees such as bananas and papayas. Monocots such as bamboo and palms may be considered trees under such a definition.[18] Despite being herbaceous[19][20] and not undergoing secondary growth and never producing wood,[21][22][22][23] palms and bamboo may produce "pseudo-wood" by lignifying cells produced through primary growth.
Aside from structural definitions, trees are commonly defined by use. Trees may be defined as plants from which lumber can be produced