There are four distinct
species of ohia tree that are endemic to Hawaii. In addition to genetic differences, environmental factors will cause physical variations in the trees. Elevation, rain, and temperature
all have an effect upon these trees.
In general, the shapes of leaves
from trees growing in hot, dry deserts are often small in order to conserve
water loss through the leaf. Contrast this to the large-leafed plants of the
tropics. Ohias occur in a wide range of habitats, from just above sea level to
8,200 feet: from dry forests with less than 16 in annual rainfall to wet
forests with more than 33 feet of annual rainfall. This along with its
genetic propensity for variation will produce trees of diverse appearance. The
species name, polymorpha which actually means many forms has eight varieties. Thus tree
height and form, leaf shape and flower color are highly variable.
Concerning the
care, ohia trees can be damaged and even killed from a lack of water. During
periods of drought especially, supplemental watering will be needed. Trees
growing in the pahoehoe lava (exhibiting a smooth, billowy, ropy surface) may do well when young and water requirements
are low. Nevertheless, as trees increase
in size, if adequate water is not supplied, they can dry out and even die. Mulch will help, but of course, not piled
against the trunk.
Since ohias are
adapted to grow in low nutrient soils, beware of over-fertilizing. Slow-release
fertilizers or natural compost is best.
