1882.] 
431 
[Trelease. 
its sweets. Instead of being rudimentary or entirely removed, 
as would be the case if they were useless, the lower stamens are 
here modified to form a most admirable support for insects ; and 
so, although no longer directly useful, they take indirectly an 
important part in reproduction. 
Acanthaceae. 
Cystacanthus turgidus (Cochin China) — The showy flowers 
are crowded in erect terminal clusters which are either simple or 
panicled. The corolla is bell-shaped above, with the throat sac- 
cate, contracted and bent below, fig. 39. The general color is 
bluish white ; the inside of the lower lip and of the sac at its 
base yellow. The sac and the five somewhat spreading lobes of 
the corolla are reticulated with purple, most conspicuous on the 
inside but visible on the outside through the translucent tissue. 
The exterior of the corolla is covered by a very fine pubescence. 
The inner face of the lobes bears scattered wavy hairs of some 
length. Only two stamens are developed; these are of equal 
length, their filaments inserted side by side on the front of the 
corolla tube just beneath the bend, and curving upward and back- 
ward so as to run across the tube, figs. 40-41. Close beside them 
are two ridges on the corolla running obliquely upward and back- 
ward, each ending in a short free end, fig. 42. These structures 
and the bases of the fertile stamens are covered with spreading 
woolly hairs. 
In a newly opened flower, fig. 40, the filaments, after crossing 
the tube, pass upward and forward so that their anthers are 
brought to lie at the top of the mouth, side by side, pointing for- 
ward and downward. Each anther is two-celled, dehiscent by 
longitudinal fissures below. The upper side is white and finely 
spinose, the lower is of a deep purple, approaching black, fig. 43. 
After dehiscence each cell is marked below by a white longitudi- 
nal stripe, the exposed pollen. The style is bent upward and for 
some distance lies closely pressed against the corolla, with its end 
just over the anthers. It bears scattered glandular hairs, espec- 
ially abundant near the end, fig. 44. 
After the flower has been open some days the positions of the 
parts change. The filaments curve downward and laterally so as 
