Abstract

1. The primary vascular system of vegetative shoots of Lupinus albus L. was analyzed by the use of serial transverse sections of plants of several ages. All the bundles evident in transections of stems are at some level related to leaves or axillary buds; they all may be designated as leaf traces or leaf-trace complexes. 2. After the phyllotaxy becomes stabilized in postseedling stages, the traces of different leaves composing the complexes show a rather constant relation to one another in terms of plastochronic intervals between the leaves the traces of which are interconnected. The median trace of leaf n is associated with the anodic lateral trace of n - 3, the cathodic lateral n with the median of n - 3, and the anodic lateral n with the cathodic lateral of n - 7. 3. The traces of the higher leaves are wider laterally than are those of the lower leaves, a feature correlated with the increase in circumference of the vascular cylinder. 4. In a given transection of a stem the bundles vary in size. The largest are the upper parts of traces nearest to this section. The smaller bundles are traces or trace complexes of higher leaves. 5. The initial development of the phloem and xylem resembles that previously recorded for many other dicotyledons. The notable feature of xylem differentiation is that, as the plant grows taller, an increasing number of xylem strands become connected with the secondary xylem rather than with the primary xylem of other leaf traces.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call