Phytomers are functional units of a plant, continually produced by root and shoot
meristem
In cell biology, the meristem is a structure composed of specialized tissue found in plants, consisting of stem cells, known as meristematic cells, which are undifferentiated cells capable of continuous cellular division. These meristematic c ...
s throughout a plant's vegetative life-cycle. Increases in a phytomer can be measured using the rate of
phyllochron The phyllochron is the intervening period between the sequential emergence of leaves on the main stem of a plant, also rendered as ''leaf appearance−1''. This measurement is used by botanists and agronomists to describe the growth and developmen ...
(rate of appearance of leaves on a shoot). Related to the phyllochron is the
plastochron As the tip of a plant shoot grows, new leaves are produced at regular time intervals if temperature is held constant. This time interval is termed the plastochron (or plastochrone). The plastochrone index and the leaf plastochron index are ways of ...
, which is the rate of leaf primordia initiation. Since many more leaf primordia are initiated than leaves develop, the plastochron develops at a much faster rate (sometimes as much as twice as quickly) as the phyllochron.
Initially, a young plant will only produce phytomers at its apical meristems but later in development, secondary meristems will begin to form and phytomers will be formed on this lateral plant growth.
References
* Howell, S.H. (1998).
Molecular Genetics of Plant Development'. Cambridge University Press 104.
* McMaster, G. S. Phytomers, phyllochrons, phenology and temperate cereal development. J. Agric. Sci. 143, 137 (2005).
Plant anatomy
{{Plant-morphology-stub