20 
soms on the same day, or single blossoms on two, three, or four suc- 
cessive days, or with an interval of from a day to a week between 
blossoms. Only very rarely do as many as three blossoms of a single 
cluster open on the same day. 
On mature vines blossoms have been noted in the spring from 
growth made as late as the preceding October. 
Four inflorescences, the buds of which were noted as pushing out 
on December 29, opened their first blossoms February 23, 25, 26, and 
28, while of six others breaking through on January 4, two opened 
their first blossoms on March 5, two on March 7, and the others on 
March 9 and 12. This showed a period of approximately two months 
to elapse between the pushing out of the inflorescence bud and the 
opening of the first blossom. 
Description of blossoms. — The flowers are borne in a spike or 
raceme sometimes branching and forming a panicle. The inflores- 
cence is centripetal and usually axillary, but occasionally it terminates 
a long stem. The waxen, pale-green blossom is borne at the apex of 
the ovary, which is 4 to 5J centimeters long at blossoming. This is 
subtended by an ovate bract about 5 millimeters long and 4 milli- 
meters broad at the base. The five spreading segments of the peri- 
anth are rather similar, 6 to 6J centimeters long, 1.3 to 1.5 centi- 
meters broad, unsymmetrical, elliptical-spatulate, and not much re- 
curved. The midrib at the back of the two petals is about 3 milli- 
meters shorter than the petal, its tip not adnate for 1 to 2 millimeters 
and recurved. The trumpet-shaped labellum, or lip, which is united 
with the column, is about 5 centimeters long and 1.5 centimeters in 
diameter. The disk of the lip is yellowish-green and verrucose, with 
a central crest or tuft facing the essential organs. The margin of the 
lip is unevenly dentate. The column is about 5 centimeters long. 
(See PL III, fig. 1.) 
Hand-pollination. — In order that the explanation of the steps in 
hand-pollination may be more readily understood, in Plate III, figure 
2, a cleared and magnified column x is shown in progressive stages of 
pollination, beginning with the organs untouched at the left and show- 
ing the pollination completed at the right. At the apex of the col- 
umn hangs the anther bending over the stigma, which consists of a 
large single lobe representing one carpel and two smaller united lobes 
representing two carpels. The large lobe covers the smaller ones and 
protrudes beyond them. As its dorsal surface is toward the anther, 
pollen is effectually prevented from reaching the stigma without out- 
side aid. The bristly crest or tuft within the lip and opposite the 
essential organs is the provision for inducing departing insect visitors 
to cross the stigma and anther and so deposit and collect pollen, but 
as the vanilla blossom does not attract insect visitors, hand-pollination 
must be resorted to. 
1 Of a species with larger blossom than V. planifolia. 
