4o8 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
23. Wernham, H. F. Floral evolution: with particular reference tci the sympetalous 
dicotyledons. IX. New Phytol. 11 : 373-397. 1912. 
24. Zinger, N. Beitrage zur Kenntniss der weiblichen Bliithen und Inflorescenzen bei 
Cannabineen. Flora 85: 189-253. 1898. 
EXPLANATION OF PLATES 
The figures in the plates are greatly enlarged. The (lower sections range from 0,5 
mm. to 3 mm. in diameter, or 3 mm. x 5 mm. in dimension. 
Plate XV 
Ulmus americana 
Fig. I. Habit sketch of flower with 8 perianth lobes and 8 stamens. 
Fig. 2. Portion of perianth showing small inner lobe {a) and vascular supply to lobes. 
Fig. 3. Longitudinal section of flower in median posterior-anterior plane. Origin 
of vascular supply {h) to perianth {p) and to stamens (5); i, bundle to anterior carpel; 
bundle to posterior carpel; ov, to placenta; i, to ovule in anterior carpel; z\ the abortive 
bundle to suppressed ovule in posterior carpel; 0^ and 0-, placental branches passing through 
the inner faces of the styles; d^, abortive bundle alternating with those to the stamens. 
Fig. 4. Longitudinal section of flower perpendicular to the plane of that in figure 3; 
dr, d'^, abortive bundles alternating with stamen bundles; e, abortive bundle in the carpel 
supply. 
Fig. 5. Transverse section through pedicel; st, the stele. 
Figs. 6-15. Transverse sections through a flower, 40, 50, 30, and (figs. 9-15) 20 microns 
apart respectively. Posterior trace passes off and separates into traces to perianth lobe (w) 
and stamen (5). Other traces pass off successively toward the anterior side, m\ n^, . . . m', 
ff, and each separates as does the posterior trace. Stamen trace aborts 70 microns above 
its origin; d^ . . . c?^, abortive bundles of vascular supply continuing above and alternating 
with that to the stamens; c, staminal cylinder; /, traces continuing into the pistil. 
Plate XVI 
Figs. 16-18. Transverse sections of flower; m . . . w? and n . . . v?, bundles to 
perianth and stamens respectively. The posterior (m) and anterior {m'') bundles separate 
each into 3 strands; i,to posterior, i^, to anterior carpel; strands 0 come together making 
0 + 0 of the placental vascular system. 
Figs. ig~2j. Transverse sections through upper part of pistil; i and dorsal bundles 
to carpels; i, to ovule; i^, abortive bundle corresponding to i; 0^ and O", inner lateral 
bundles of styles. 
Fig. 22. Section through a flower at level of stalk of pistil, an 8-merous flower. 
Fig. 23, Section through a flower with 7 perianth lobes and 6 stamens. 
Fig. 24. Section through a 9-merous flower. 
Fig. 25. Section through a flower having a stamen (nk) with no accompanying peri- 
anth lobe. 
Plate XVII 
Ulmus fulva 
Fig. I. Median longitudinal posterior-anterior section; supply to stamens originates 
some distance (6) above that to perianth; 0, the placental strand which branches like that 
in U. americana (Pl. XV, fig. 3) ; d, abortive bundles. 
Fig. 2. Transverse section through lower part of flower; p, perianth; s, stamens; 
d, abortive strands; s^, abortive (lignified) strand to suppressed stamen; continuation 
of floral axis above the stamen supply. 
Ulmus racemosa 
Fig. 3. Median longitudinal posterior-anterior section of flower; h, origin of perianth 
{p) and stamen (5) strands; 0, placental supply. 
