Phloem in the Stems of Dicotyledons. II. 429 
Podospermum laciniatum, DC. 
Stem. 
Herbarium material only. 
Very numerous small phloem-strands occur in the pith, aggregated 
towards the centre : none occur at the periphery. 
P. calcitrapifolium, Boiss. 
Stem. 
Herbarium material only. 
No medullary bundles or phloem-strands were found. 
Scolymus. 
Stem. 
This genus possesses numerous small phloem-strands at the periphery 
of the pith, which are continuous into the branches. Opposite the leaf-trace 
bundles they are in the form of vascular bundles of much larger size, which 
unite with the vascular ring after the leaf-bundles ‘exit’. The medullary 
phloem-strands, if traced downwards into the base of the stem, become fewer 
in number, and, for the most part, well-constituted amphivasal bundles. At 
the lowest level, i.e. immediately below the entrance of the lowest leaf- 
traces, they die out in situ . The phloem-strands (a bundle here and there 
amongst them) persist into the highest part of the stem and peduncle, and 
go to form part of the supply system of the capitulum. 
.S', macidatus , L., was the species examined specially for the course of 
the strands. 5. hispanicus , L., has essentially the same structure. 
Leaf. 
There is a simple arc of large, widely-separated bundles. There is no 
trace of intraxylary phloem in any part of the petiole or midrib. 
This is, therefore, one of the rather rare cases in which the leaf exhibits 
a more advanced, i.e. reduced, structure than the stem. 
Picridium tingitanum, Desf. 
Stem. 
Kruch found medullary strands in this plant. The present writer 
found that the three specimens which he examined from the Herbaceous 
Ground at Kew were entirely devoid of them, save for the invagination into 
the pith of two amphivasal bundles in the lower end of one of the branches. 
Leaf 
There is a simple arc of large bundles alternating with very small 
vestigial ones. 
