6 BULLETIN 1195, V. S. DEPARTMENT OF AGRICULTURE. 



medium very few grains germinated. This species gave the most 

 vigorous and liighest percentage of germination seen in any of the 

 tests (PI. II, fig. 1). ^ 



Solanum fendleri. — The anthers oi S. fendleri possess large pollen 

 chambers (PI. 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 snriveled and 

 empty. Tnere was always good germination, however, with many 

 tubes as long as 800 n (PI. 11, fig. 2). 



Solanum jamesii. — The pollen chambers in the anthers of S. 

 jamesii are rather narrow (PI. I, fig. 8), 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 tlie 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 GOO m in length. 

 There was more pollen sterility in this species than in the two pre- 

 viously noted (PI. Ill, fig. 1). 



Solanum ma(jlia.-—The anthers of all plants of iS. maglia grown at 

 Presque Isle in 1922 were well matured, deliiscence 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 (PI. Ill, fig. 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. 



AXTHKRS AND POLLEN OK CULTIVATKI) VARIETIES. 



Special stud}- was made of the anthers and pollen of healthy 

 plants of 132 named varieties, chiefly commercial, from diflerent 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, phmipuess, and dehiscence of stamens, and in the 

 (juantity 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 

 sporogcnous tissue. 



On the basis of the condition of the anthers, the (juantity 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; dehiBcence very resriilar 

 and complete: pollen abundant with at least .W per cent becoming jiliimp and contain- 

 ing granular material; germination good with pollen tul)e8 on culture media often .JOO 

 M in length but seldom more than 1') to 20 per cent of all grains germinating. 



The Mc("ormick and Rusola may he. considered in detail as two of the varieties with 

 the best development of anthersaTid [)ollen. Tlie anthers arc largeand w(^ll (ievelo|)ed, 

 the pollen chamlxjrs are ample (I'l. 1. lig. 4), and dehiscence is e.vcellent. Pollen 

 is abundantly shed, and about half of all pollen grains contain granular material 

 and l)ecome plumj) on the media used in testing germination. On the 15 per cent 

 sugar plus 1 percent agar medium, which gave the best germination, there was germina- 

 tion of 5 to 10 per cent of all grains, with tubes often ."lOO n in length. Al)out half of 

 the pollen is shriveled and empty and does not fill out plumply when placed on the 





