readily z'eveals the presence of pollen tnbes. (Sec PIuIl^ 1 and 2). The 

 relative number of grains that germinate can be determined. 



A study of the condition of pollen is facilitated further by the ad- 

 dition of aceto-carniine stain and especially when there is very poor or 

 no germination. The stain shows that pollen grains may swell up and 

 be plump in water and on the medium used for germination tests and 

 yet contain very little granular .material or none at all. In other cases 

 pollen grains may be so aborted that they remain shrunken and col- 

 lapsed. Sometimes, however, pollen grains that appear to be good do 

 not germinate (See Plate 2). 



In respect to the condition of the pollen and its viability and its 

 ability to function in seed production when used properly, varieties 

 may he classed as follows: 



a. Pollen excellent; anthers well-formed, dehiscing properly, pol- 

 len abundant, high percentage of germination when grown in 

 culture tests. In controlled pollination such pollen frequently 

 results in seed pods. 



b. Pollen good; anthers well-formed, dehiscing properly, pollen 

 abundant, fair percentage of germination in culture tests. In 

 controlled pollination such pollen occasionally results in seed 

 pods. 



c. Pollen appearing good, anthers well-formed, dehiscing properly, 

 pollen abundant, when grown in culture tests little or no ger- 

 mination but apparently sometimes able to produce seed. 



d. Pollen scant, or none, anthers not well-for.med, if pollen is pres- 

 ent it does not dehisc but is "caked," 



Irregularities in the character of stamens and pollen are to be 

 found among the flowers of certain varieties and even for different flow- 

 ers of a same stalk. Thus Amabilis had very little pollen in flowers 

 that opened on May 2()th, hut viable pollen was collected from flowers 

 open on May 29th. In the case of Golden Plume no pollen was found 

 in flowers open on June 9th, but on June 20th, pollen was obtained 

 which gave 40% germination. No pollen was found for Queen of May 

 on May 27th, three days later considerable pollen was being shed which 

 gave about 10% germination but on June 2nd and June 12th the flowers 

 open on this variety seemed to be pollen sterile. Such variations arp 

 apparently characteristic of certain varieties and may, in part at 

 least, be due to external influences such as unfavorable weather condi- 

 tions. For most varieties of the "a" class the pollen appears to be very 

 constantly potent. 



The Iteport <il the Data (Htfain^Ml 



It seems advisable to give the (lat;i of the investigations in the 

 two tables that follow. For convenience the varieties are arranged in 

 alphabetical order using the names given in the American Iris Society, 

 Preliminary Complete Check List, Seventh Revisit)!!, Jan. 1. 1922. The 

 varieties were worked as known in the test garde!i and gi'ouped under 

 the p!-eferred name as listed in the check list. No attempt has bee!! 

 !na(le here !<• group \ai"ieties accoi'diiig to the botanical o!" natiii'al !"c»- 

 latio!iships. 



