MARTIN, F. W. (Federal Experiment Station, Mayaguez, Puerto Rico 00708). Pollen germination oll foreign stigmas. Bull. Torrey Bot. Club 97: 1-6. 1970.-Although pollens of many species ger minate in simple aqueous media, stigmas do not provide satisfactory sites for germination of most foreign pollens. In crosses among 24 unr elated species, only 4.3 % resulted in pollen germination. In intrageneric crosses of Solanum and Ipomoea, the percentage of combinations in wvhich germination occurred was 42% and 25%, respectively. Although pollens germinated most frequently in crosses of closely r elated species, sometimes germination occurred in very distant and unpredictable crossing combinations. Thus, stigmas not only provide the proper conditions for germination of pollen from their particular species but also actively inhibit the germination of polleni of many unrelated species.