86 BOTANICAL GAZETTE [SEPTEMBER 
have a conspicuous sheath, sharply marked off from a limb, from 
which it may or may not be separated by a distinct petiolar region. 
Fig. 9 represents the leaf of Streptolirion volubile Edgw., in which 
all these parts are well developed. In Commelina, Aneilema, and 
Tradescantia there is a striking range of form in the limb, which 
in different species shows (within each genus) gradations from 
linear to ovate. 
Pontederiaceae 
Fig. 8 A represents what is perhaps the most complex type of 
leaf met with in the Farinosae, that of Eichhornia speciosa Kth. 
(Pontederia crassipes Mart.). The ligular sheath (lig. s, fig. 8 A, B) 
with its lobed apex, almost suggesting a second leaf blade, to which 
attention has been drawn by Gttick (12), is, as he points out, 
unparalleled among monocotyledons; it may perhaps be remotely 
compared with the curious frill-like top of the ochrea of a Poly- 
gonum from Java, figured by VELENOvskKY (18, fig. 277). The petiole 
of E. speciosa is dilated, and terminates in a limb, which, as shown 
in a previous paper (1), possesses both normal and inverted bundles 
(fig. 8C). In this paper it was recorded that inverted bundles 
occurred in the limb of Eichhernia, Pontederia, and Heteranthera. 
The family also contains three other genera, Monochoria, Reussia, 
and Hydrothrix. In Monochoria plantaginea Kth. I have now 
been able to observe that inverted as well as normal strands occur, 
and in a very small fragment of the leaf of Reussia subovata Solms, 
the only material available from this genus, I again found both 
types of strand. It has thus been possible to establish the occur- 
rence of inverted strands in five genera of the Pontederiaceae; 
the sixth, Hydrothrix, is an aquatic plant in which it is useless to 
look for this anatomical peculiarity, since, as GOEBEL has shown, 
the leaf is so much reduced as to be traversed by one vascular 
strand alone (1). 
The shape of the limb in the Pontederiaceae ranges from the 
narrow, almost linear form sometimes met with in Monochoria 
plantaginea, to broader types with a cordate base, such as Ponte- 
deria nymphaefolia Kth., or with an auricled base, such as that 
illustrated in M. hastaefolia Presl (fig. 7). 
