28 MR. R. H. COMPTON : AN INVESTIGATION OF THE 
CYTISUS PURPUREUS, Scop. 
Fair-sized shrub. Cotyledons ovate. 
In this and the other Cytisinee examined the root contains a continuous 
biseriate diarch plate of xylem lignified throughout at the end of the first 
phase of growth (cf. Pl. 5. fig. 75 of C. canariensis). The phloems contain 
fibres. Broadening of the xylem begins just above the collet, and a Y-shape 
is attained about a quarter of the way up the hypocotyl, changing toa T-shape 
half-way up. The T-shape persists to within 5 mm. of the cotyledons, then 
breaking up into a triad ; the lateral metaxylems quickly combine with the 
half-phloems to form collateral bundles. In the cotyledons these bundles 
fuse in the median plane when the pinnation of the midrib begins. 
CYTISUS HIRSUTUS, Linn. 
Moderate-sized shrub. Cotyledons ovate. 
The transition phenomena are very closely similar to thosein C. purpureus, 
but take place rather more slowly, with the results that the T-shape of xylem 
does not extend over so great a distance, and that the collateral position of 
the lateral metaxylem of the cotyledon trace is only attained about 1 mm. 
below the node. 
CYTISUS CANARIENSIS, Steud. (РІ. 5. fig. 75.) 
Cotyledons ovate. 
The transition phenomena so closely resemble those in C. hirsutus that 
there is no need to describe them in detail. It may be noted that the 
cotyledon trace retains signs of doubleness long after its pinnation, not as in 
C. hirsutus, &c., where it becomes a single median collateral bundle at the 
region of branching. The changes are hardly complete at the node, stem- 
like collateral bundles not being fully organised, so that the transition is best 
described as intermediate-high. 
ULEX EUROPÆUS, Linn. (Pl. 1. fig. 16.) 
Thorny bush, with leaves and branches reduced to spines except in early 
life. Hypocotyl tapering gradually to the long primary root. Cotyledons 
only just above ground, oblong-ovate. 
Though starting in the same way as in other Cytisinæ, &c., the transition 
phenomena differ in being incomplete within the hypocotyl ; the bundles are 
in the “position sécantielle ? at the node, the xylems being differentiated 
tangentially. The transition must be considered intermediate-high, agreeing 
most closely with that in Cytisus canariensis. 
LUPINUS MUTABILIS, Sweet. 
A low shrub. The stout hypocotyl narrows rather suddenly to a strong 
primary root. Cotyledons large and fleshy, rather lop-sided owing to the 
accumbent folding of the embryo in the seed. 
