430 GROWTH OF PLANTS 



Cinchona pollen at 10° C (50° F) lived a year with relative humidity of 35 

 to 50, gave 3 per cent germination in 3 months with 65 per cent R,. H., and 

 2 to 3 per cent after 6 weeks with 25 per cent R. H. Gladiolus pollen kept 

 best at 10° C (50° F) with 40 to 50 per cent R. H., but degenerated rapidly 

 in open air storage at room temperatures. Pollen of most varieties used 

 kept 8 to 10 weeks under this condition and pollen of a few varieties showed 

 live grains after 102 days. Lilium pollen kept as long as 7 months when 

 stored at 10° C (50° F) with controlled humidity; L. auratum best at 

 35 per cent R. H. ; L. speciosum best at 50 per cent R. H. ; and L. longiflorum 

 at 65 per cent R. H. Under the same conditions the Amaryllis hybrid 

 pollen lived for 5 months. Under similar conditions Lilium pollen in 

 gelatin capsules wrapped in paraffin paper at —10° or — 11°C (14° or 

 12° F) kept well. Sealed vacuum storage at 5° or -5° C (41° or 23° F) 

 was unfavorable for Cinchona but favorable for Lilium pollen. As with 

 seeds, the longevity of pollen can be increased greatly by improving storage 

 conditions. Constant humidity is important in both, but in many seeds 

 much lower humidities are favorable. Likewise, lowering the temperature 

 is beneficial in both. Absence of oxygen is beneficial in dry seeds. The 

 evidence for this on pollen is not clear. It would be interesting to know the 

 optimum of all three of these factors for several pollens and to learn how 

 much the life span could be increased by putting all these factors at the 

 optimum. 



In hybridization several species of lilies show maternal characters. This 

 is true of L. superhum L. and L. auratum Lindley. In spite of this, Pfeiffer ^^ 

 in her lily hybridization work got some hybrids with these two species as 

 maternal parents that combined the characteristics of both parents. This 

 was true of L. auratum 9 with both L. ruhellum Baker and L. japonicum 

 Thunberg as pollen sources. The same was true of L. superhum 9 with 

 L. canadense as the pollen source. Intermediate forms ^^ were also obtained 

 with L. sulphureum Baker as seed parent and L. Henryi Baker as the 

 pollen source. 



McLean and McLean ^^ got reciprocal crosses between Lilium tigrinum 

 Ker-Gawl., noted for its sterility, and two different lily hybrids, L. X um- 

 hellatum and L. X elegans. The new hybrids showed characteristics of both 

 parents and produced viable seeds. McLean ^^ produced a bigeneric hybrid 

 by using the pollen of the garden hybrid gladiolus "Byron L. Smith" on 

 Antholyza revoluta Burm., the Rood Jvapje of South Africa. The hybrids 

 showed strongly the vegetative and flowering characters of the pollen 

 parent, but the seed parent habit of winter growth during short daily illu- 

 mination and low temperatures. The hybrids produced no viable pollen 

 and did not produce seed when pollinated from either South African or 

 American gladioli. McLean ^^ produced a scented hybrid gladiolus ap- 

 proaching in stature and flower size our summer flowering gladioli. He 

 designates it as Z-36 and describes it as "being derived on the one hand 

 from a garden hybrid gladiolus, 'Gretchen Zang,' as pollen parent, and 



