116 MISSOURI BOTANICAL GARDEN. 
Y. filamentosa at Washington and St. Louis begins bloom- 
ing about the middle, of June, and is usually through 
blooming about the middle of July. In Philadelphia, so 
near to Washington, it blooms nearly two weeks later. 
Y. angustifolia blooms from a fortnight to three weeks 
earlier, so that it has almost ceased to bloom before jila- 
mentosa begins. Pronuba yuccasella is restricted in its 
appearance in the imago state, and in the eastern portion 
of the country appears coetaneously with the flowering of 
Yucca jilamentosa, the males almost always being seen 
first. Thus both at St. Louis and at Washington 
Yucca angustifolia does not ordinarily set fruit, because 
it flowers before the Yucca moth appears. Occasionally, 
however, this last is about when some of the latest or 
terminal flowers are open, and I have known a few pods on 
the tip of the panicle of this species:to be fructified in St. 
Louis. So in the more northern States, where Yucca aloi- 
folia is cultivated, it blooms too late to be pollinized, and I 
have never known it to set fruit. 
In South Carolina, as Dr. J. H. Mellichamp informs me, 
there is even greater irregularity in the blooming of Y. jil- 
amentosa, though the genuine or more typical form blooms 
a month earlier than at Washington. This is pollinized 
by Pronuba; but some varieties bloom earlier or later — 
even in autumn. In these later bloomings Dr. Mellichamp 
has never known fruit to be produced. The variety levi- 
gata usually blooms two weeks later, and the variety brac- 
teata still later than the typical form. 
Yucca aloifolia blooms in the south in June and July and 
the earlier blooming specimens are pollinized by Pronuba. 
Yucca gloriosa flowers in the south still later (September 
and October) and rarely sets fruit. It is very irregular, 
however, and on one occasion Dr. Mellichamp found a 
plant blooming in June in an old sandy fleld. This was 
the only plant he ever saw blooming in summer, and it 
produced fruit. I have seen a form of it blooming in 
March, with no sign of fructification. 
