Plant Phenology And Itsrelation TO The Cool Semi-Arid Conditions OF Sana'a

Abstract

In the cool semi-arid highland areas of Sana'a, a plant
phonological study of forty two species revealed that there was one
major outburst of plant emergence corresponding with the first period
of the heavy rainfall which take place during March-April. The second
period of heavy rainfall which takes place during July-August shows
moderate effect on emergence and growth.
Plant Species included annuals, biennials and perennials. Perennials
showed
the
following
growth
forms
hemicryptophytes,
chamaephytes, phanerophytes, and cryptophytes. Most plants where
herbaceous and a few where woody
Different Individuals of the same species could behave as annuals,
biennials or perennials. In areas where soil moisture lasted for a short
period, plants behaved annuals, and in areas where moisture lasted for
longer periods, the plants behaved as biennials or perennials. The
prolonged period of leafing, flowering and fruiting experience by most
species also was caused by the moderate temperature which prevailed
during the year
Leafing, flowering and fruiting periods varied among species.
However, they prevailed from March to November. Growth of most