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In this article we will discuss about the external features of marsilea.
1. Plant body (Fig. 258) is sporophytic and the sporophyte possesses a rhizome; having man) roots arising towards lower side and leaves towards the upper side.
2. Rhizome is long, slender, well-branched and grows on or below the soil surface and may attain a length of several metres in some species.
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3. Rhizome is divisible into nodes and internodes. Roots and leaves arise from the nodes. Though roots may also arise occasionally from internode.
4. Roots are adventitious, branched or unbranched and arise strictly in acropetal succession on the nodes of rhizome.
5. Leaves are long, compound, arise on the nodes and remain arranged alternately in two rows on the rhizome.
6. Each leaf consists of a long, slender petiole having four leaflets or pinnae at its apex. But according to Puri and Garg (1953) the leaf or vegetative part of Marsilea does not contain four leaflets but only one leaflet bearing four pinnules.
7. Leaflets may vary from 3 to 8 in number in different species.
8. The young leaves are circinately coiled and all the leaves on the rhizome develop in acropetal succession.
9. Many unbranched and multicellular hairs are present on young parts in some species, e.g., Marsilea minuta.
10. Leaflets are obovate or elliptical in shape with smooth or toothed margins.
11. Out of the four leaflets, two lower ones are arranged in a pair while the upper two leaflets are arranged alternately (Fig. 259 A).
12. Many dichotomously branched veinlets are present in each leaflet. Veinlets are connected with cross connections (Fig. 259 B).
13. Veinlets are attached to one another on the margins with the marginal loops.
14. Many bean-shaped or oval, reproductive bodies are attached to the petiole with the help of their peduncle. These are called sporocarps.
