1913] GOW—MORPHOLOGY OF AROIDS 135 
the entire microsporangial structure was fully matured at that 
time; the mother cells had disappeared and the pollen grains were 
found lying free in the loculi of the anther. Almost all the bulbs 
were such as had borne pistillate blossoms the preceding season; 
in fact the material was collected after the early frosts and was 
discovered by means of the conspicuous clusters of bright red 
berries after the withering of the leaves. A very few of the bulbs 
were laterals formed from the central bulb during the growing 
season. Two or three of the bulbs collected contained a monoecious 
spadix. Two-thirds of the balance contained staminate blossoms 
only. Arisaema seldom bears staminate and pistillate flowers on 
the same spadix, but the indication is that the plant that bears 
pistillate flowers one year bears staminate flowers the next. It 
is, in a way, consecutively monoecious, seldom simultaneously 
monoecious. 
The loculi of the stamens contained many normal pollen grains, 
but far more small suppressed grains, the ratio being about 2:1, 
Suggesting the inability of the plant to muster sufficient energy 
to mature all the pollen it produces. 
11. Richardia africana 
This plant, the Calla aethiopica of the florists, was found in 
every stage of development at the Cedar Rapids greenhouses, 
and fixation proved extremely easy owing to the absence of mucilage 
in the tissues. 
The upper portion of the slender spadix is covered by a densely 
crowded mass of stamens, while the pistillate flowers occur below. 
Scuott describes the pistils as “organis neutris tribus cincti,” 
but in perhaps a fourth of the blossoms these “neutral organs” 
turn out to be functioning stamens, while in the remainder they 
are staminodia, or staminal rudiments. 
The cylindrical ovary consists of 2, 3, or 4 carpels, the anat- 
ropous ovules being borne on the central placenta, which here 
represents the united carpellary walls. Two to four ovules occur 
in each carpellary cavity (fig. 32), and a separate branch of the 
open stylar canal runs to each cavity. The ovule is anatropous, 
and of foliar origin, since it springs from the carpellary wall. The 
