Finally the cauline meristeles themselves may be resolved into a number of fine threads.
The vascular supply of the leaf (leaf-trace) consists of a single strand only in the haplostelic and some of the more primitive siphonostelic forms. In the microphyllous groups Leaf.trace of Pteridophytes (Lycopodiales and Equisetales) in and Petlolar which the leaves are small relatively to the stem, the Strands, single bundle destined for each leaf is a small strand whose departure causes no disturbance in the cauline stele.
The protoxylem of each is a leaftrace, while the metaxylem consisting of a right and a left portion forms a quite distinct cauline system.
In addition to these cauline (fi rstcell).(After strands (confined to the stem and not connected Webber.) with the leaves), collateral bundles are often met with in the pith, which form the vascular supply of terminal flowers borne at intervals on the apex of the stem.
Only the median or carinal strand of xylem is common to stem and leaf; the lateral cauline strands possibly represent the remains of a centripetally developed mass of primary xylem.