In this article we will discuss about the morphology of ephedra with the help of a suitable diagram.
Ephedra, with about 35 species, is a widely distributed xerophytic dioecious plant. Many of its species are highly branched shrubs, switch-plant, and one E. triandra, even approaches the tree form. A common form E. girardiana (Fig. 17.1 A) is ornamental, with one to many short and thick stems and profuse branches, so that the entire plant appears as a hemispherical mass of thin green stems. Another cultivated ornamental E. campylopoda, is pendulous and is grown in hanging baskets. It is able to spread by means of rhizomes that grow from its underground buds.
Ephedra (Fig. 17.1 A) in its external appearance is similar to Equisetum. The stem is capable of elongation by means of inercalary meristem, at the base of each internode. Long internodes are ridged and the ridges on successive internodes alternate, so also the leaves at successive internodes. There are similarities between Ephedra and Equisetum in terms of jointed stem, an intercalary (Fig. 17.1D) meristem, reduced and whorled leaves (Fig. 17.1B,C).
These similarities in external morphology are suggestive of a phylogenetic relationship. It should also be noted that sporangiophores in Equisetum are not different from those present on the male cone of Ephedra. These similarities are described to be the result of parallel development.
The branches are of two types: indeterminate and determinate. However, the distinction between the two is not so well-marked as in Pinus. Photosynthesis is carried out by the green stem. The leaves are small, scaly, thin and fuse to form a basal sheath at the node (Fig. 17.1B,C). Young leaves are green but are brown at maturity. The leaves at the nodes are in whorls of 3-4 at indeterminate branch, whereas leaves are opposite and in decussate pairs on a determinate branch.