84 BOTANICAL GAZETTE [SEPTEMBER 
Griseb. var. minor, and find them to be traversed by a single 
series of normally orientated bundles, corresponding to those in 
the sheath leaves of Xyris gracilis (fig.17 C). A. Poarchon, as figured 
by SEuBERT (17), has an acuminate apex to the foliage leaf, while 
it also has bracts which terminate in a “cornet,” recalling that 
described by Hatter in the case of the sepals of certain dicotyle- 
dons (see reference and discussion, 10). It is probable that the 
apex in both foliage leaf and bract of A. Poarchon Seub. is a vestigial 
petiole, and is morphologically equivalent to the ensiform limb 
of Xyris. 
Eriocaulaceae 
The Eriocaulaceae have both cauline and radical leaves of a 
simple type. The two principal genera are Eriocaulon and Paepal- 
anthus, both of which include more than a hundred species. Fig. 
19 A shows the general internal structure of the “British species of 
Eriocaulon, E. septangulare With. A large proportion of the 
leaf is occupied by lacunae, separated by lamellae, each of which 
includes a single normally orientated bundle. Fig. 19 B shows one 
lamella with its vascular strand on a larger scale. A fragment of 
a diaphragm (d) with intercellular spaces between its cells is seen at- 
tached to the lamella on one side. In E. cuspidatum Dalz. the limb 
terminates in a mucro (fig. 19 D), while in EF. Wallichianum Mart. f. 
submersa the tip of the ribbon leaf is minutely truncate (fig. 19 C). 
In this aquatic species, as in so many water plants, there is an 
increase of the tracheal tissue near the leaf apex, and there are 
indications of water stomates and possibly an apical opening, but 
in herbarium material it is difficult to identify these structures 
with certainty. The leaves of certain species of Eriocaulon may 
be much reduced; in the aquatic E. setacewm L. the fragile linear 
leaf, traversed by a single bundle, recalls that of Mayaca. In 
the case of Paepalanthus I have examined one species, P. speciosus 
Gardn. Here, as in Eriocaulon, there is one series of normally 
orientated bundles in the leaf. The large epidermal cells are a 
striking character. 
Rapateaceae 
The leaves of this family are much larger and more complex 
than those of the Eriocaulaceae; they may show a definite differ- 
