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SEEDLING STRUCTURE IN THE LEGUMINOS.E. 17 
only just below the cotyledonary node, the greater part of the hypocotyl 
having a very uniform structure (cf. Acacia). 
CASSIA LÆVIGATA, Willd. (Pl. 2. figs. 46-50.) 
Erect shrub. Hypocotyl tapering gradually to a long tap-root. Cotyle- 
dons ovate. 
The root is tetrarch ; the shape of the solid xylem star is a little unusual, 
the arms being 3-4-seriate, and there being a deep sinus between each 
pair of arms in which lies the phloem (fig. 46). A pith begins to appear 
about 5 mm. below the collet, and at the collet the xylem is spread into a 
continuous tangential ring surrounding the pith, with four projecting proto- 
xylems (fig. 47). As we ascend the hypocotyl the ring becomes broken into 
four triads, each composed of a median protoxylem and a pair of metaxylems 
(fig. 48). This condition is found through the greater part of the hypocotyl, 
but the quantity of xylem diminishes from below upwards. The phloem 
remains unchanged throughout, never undergoing division. The metaxylems 
fuse in pairs about 2 mm. below the cotyledonary node, and the lateral proto- 
xylems divide immediately after, the polar protoxylems remaining in situ 
(fig. 49). The metaxylem at this level has become completely endarch. 
The cotyledon trace consists of a median protoxylem and a pair of broad 
endarch collateral bundles bounded externally by pericyle fibres (fig. 50). 
CASSIA FLORIBUNDA, Cav. 
Erect shrub. Cotyledons ovate. Agrees with C. levigata iu all essential 
respects. 
CASSIA BRASILIANA, Lam. 
Tree. Hypocotyl tapering very gradually to a long primary root. Cotyle- 
dons ovate, prominently palmately veined. 
The hypocotyl is of rather hard consistency, owing to the cortical 
mechanical zone, the pericycle fibres, and the fibrous development of the 
perimedullary zone. 
CASSIA SIAMEA, Lam. 
Low tree. Cotyledons ovate. 
CASSIA SUMATRANA, Ztocb. 
Low tree. Cotyledons ovate, midrib dichotomising half-way along. 
These two species, said by the Kew Index to be identical, show no novel 
points of structure beyond those already mentioned. 
LABICHEA LANCEOLATA, Benth. 
Shrub or sub-shrub. The hypocotyl contracts remarkably from a diameter of 
LINN. JOURN.—BOTANY, VOL. XLI. C 
