6 BULLETIN 1195, U. S. DEPARTMENT OF AGRICULTURE. 
medium very few grains germinated. This species gave the most 
vigorous and highest percentage of germination seen in anv of the 
tests (PI. II, fig. 1). 
Solarium fendleri. — The anthers of S.fendleri possess large pollen 
chambers (PL I, fig. 2), with an abundance of pollen. Examination 
and tests for germination were made of pollen of 32 different plants. 
There was a rather wide variation in the size of the pollen grains 
that were plump, and there were always some grains shriveled and 
empty. There was always good germination, however, with many 
tubes as long as 800 m (PI. II, fig. 2). 
Solarium jamesii. — The pollen chambers in the anthers of S. 
jamesii are rather narrow (PL I, fig. 3), in comparison to those of 
S. chacoense. The anthers dehisce fully and shed an abundance of 
pollen. Examinations and tests for germination were made of the 
pollen of 21 plants. Two of these plants produced only a few plump 
grains, none of which germinated; for the others, the quantity of 
aborted pollen ranged from one-tenth to two-thirds of all grains, but 
the germination was excellent with tubes as much as 600 m in length. 
There was more pollen sterility in this species than in the two pre- 
viously noted (PL III, fig. 1). 
Solarium maglia.— -The anthers of all plants of S. maglia grown at 
Presque Isle in 1922 were well matured, dehiscence was excellent, 
and pollen was abundant. Only five plants bloomed during the 
period of the study of pollen, and at least 90 per cent of the grains 
of these were empty and shriveled (PL III, ng. 2). In numerous 
tests for germination involving many thousands of grains only a few 
short pollen tubes were observed. The plants of this species which 
were studied appeared to be almost, if not completely, pollen sterile. 
ANTHERS AXD POLLEN OF CULTIVATED VARIETIES. 
Special study was made of the anthers and pollen of healthy 
plants of 132 named varieties, chiefly commercial, from different parts 
of the world and of 78 seedlings, all grown at Presque Isle. Noticeable 
differences were found in the relative lengths of pistils and stamens, 
in the size, color, plumpness, and dehiscence of stamens, and in the 
quantity of pollen and its viability. In decided cases of abortion and 
impotence of stamens the anthers are green or pale green through- 
out at the time of full maturity, with no dehiscence and little or no 
sporogenous tissue. 
On the basis of the condition of the anthers, the quantity of pollen 
shed, the relative number of grains possessing granular contents, 
and the extent and vigor of germination of pollen, the cultivated 
varieties may be grouped into four classes, as follows: 
Class 1. — Anthers well developed, richly orange colored; dehiscence very regular 
and complete; pollen abundant with at least 30 per cent becoming plump and contain- 
ing granular material ; germination good with pollen tubes on culture media often 500 
n in length but seldom more than 15 to 20 per cent of all grains germinating. 
The McCormick and Busola may be considered in detail as two of the varieties with 
the best development of anthers and pollen. The anthers are large and well developed, 
the pollen chambers are ample (PI. I, fig. 4), and dehiscence is excellent. Pollen 
is abundantly shed, and about half of all pollen grains contain granular material 
and become plump on the media used in testing germination. On the 15 per cent 
sugar plus 1 per cent agar medium, which gave the best germination, there was germina- 
tion of 5 to 10 per cent of all grains, with tubes often 500 n in length. About half of 
the pollen is shriveled and empty and does not fill out plumply when placed on the 
