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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
but that the anterior carpel is partially abortive. However, Urtica has been 
looked upon as being "unicarpellary " (Baillon, i; Bessey, 3). 
Transverse sections of the Urtica flower indicate zygomorphy: the two 
lateral perianth parts are alike; but the posterior is larger than the anterior 
and is the last to become distinct from the shallow perianth tube (figs, i, 
10-13, m) ; the pistil does not stand in the middle of the flower. 
Boehmeria cylindrica L. (Sw.) possesses a tubular flower with the 
vascular supply of the perianth confined to the anterior and posterior sides 
(PI. XXII, figs. I, 3-7, m). This fact indicates that the lateral perianth 
parts have been consolidated with the anterior and posterior parts and that 
their vascular supplies have completely degenerated. This flower shows 
the zygomorphic features of the Urticales. 
Only two strands pass into the pistil instead of four as in Urtica gracilis. 
These two strands arise from one strand (PI. XXII, figs. 3, 4, and 0) 
in the basal portion of the flower. The posterior strand passes up the 
posterior side of the pistil into the short filiform style and is the dorsal 
carpellary bundle. The other strand ascends anteriorly for a short distance 
and then sharply curves towards the posterior; after passing horizontally in 
this direction for a short distance it abruptly ascends into the "basal" 
ovule (figs. I, 5, o). The anterior side of the pistil has no vascular supply. 
Here undoubtedly the anterior carpel is suppressed. Therefore, Boehmeria 
cylindrica has reached that stage in reduction having only two perianth 
parts, one carpel, and a "basal" ovule. The ovule from the path of its 
bundle (fig. i, 0) indicates that its apparent orthotropous nature has become 
such by a sinking down to a basal position from a pendulous or lateral 
position. 
In the base of the staminate flower, the strands of the pedicel conjoin 
(PI. XXII, figs. 9, 10, 11) and strands then pass off to the perianth and to 
the stamens (figs. 9, 12, s). The staminate flowers have an abortive 
pistil which possesses a weak vascular supply (figs'. 9, 12, i, i^). 
Laportea canadensis (L.) Gaud, has a flower that is decidedly zygo- 
morphic. The floral structures vary from those described above. The 
anterior perianth part is large, the posterior is very small, and the lateral 
parts are alike. From a cylindrical stele (PI. XXII, fig. 15) of the tiny 
pedicel a strand passes anteriorly into the anterior perianth part (figs. 14, 16, 
m). No strand corresponding to the anterior perianth strand passes off 
into the small posterior perianth part (figs. 14, 16, m}). Two strands pass 
off laterally to the lateral perianth parts. Evidently the decussate arrange- 
ment of the perianth supply as exhibited in Urtica gracilis is broken in 
Laportea canadensis through the suppression of the posterior perianth 
trace, although a very small perianth part is still present (figs. 14-19, w}). 
Above the origin of the perianth bundles only two bundles continue, 
and these in an anterior-posterior plane. The posterior bundle passes up 
the posterior side of the pistil into the single style (PI. XXII, figs. 14, 16-21, 
