摘要:

A low percentage (2 to 3%) of the flowers ofAsclepias synacaL. produce mature seed pods. Many ovaries begin to enlarge but abort before reaching maturity. Histological examination of these pods shows that ovule abnormalities accompany pod collapse. Ovules in free-nucleate endosperm stages show a growth of the integument that is excessive for ovules at this stage of embryo sac development. Older aborting ovules contained a zone of collapsed cells completely enclosing the endosperm.Seed collapse of the former type at least appears similar to cases attributed to a competition for food between endosperm and the adjacent maternal tissue of the ovule, termed "somatoplastic sterility" by Brink and Cooper.

ISSN:1923-4287    

DOI:10.1139/cjr46c-008

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

The chromosome number of eight species and varieties ofAsclepias(A.syriaca,A.incarnataand varietypulchraand formaalbiflora,A.Sullivantii,A.tuberosa,A.curassavica,A.speciosa) was found to be 2n = 22.Various interspecific pollinations were attempted without success. A cross ofA.incarnatawith formaalbiflorawas successful.Possible natural hybrids betweenA.syriacaandA.speciosaand betweenA.incarnataand var.pulchraand formaalbifloraare described. Two unusual chimaeral plants ofA.incarnatathat produced several stems of formaalbifloraare described.

ISSN:1923-4287    

DOI:10.1139/cjr46c-009

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

Two species ofAcremoniella,A.atra(Cda.) Sacc. andA.verrucosaTogn., one species ofChlamydomyces,C.palmarum(Cke.) Mason, and one species ofTrichoclacdium,T.asperum(Cda.) Harz, have been isolated from agricultural seeds and are described and illustrated. These fungi do not appear to be of serious pathological significance.

ISSN:1923-4287    

DOI:10.1139/cjr46c-010

出版商:NRC Research Press    

年代:1946

数据来源: NRC

摘要:

F1tetraploids grown in pots had larger but fewer leaves and inflorescences than control diploids. Increase in size of the organs was offset by reduction in number, so that leaf area was no greater and total number of florets per plant was much lower in tetraploids than in diploids. Fertility varied inversely with genetic relationship and was much reduced in the tetraploids. No significant differences were noted in root size. The tetraploids grew slightly more slowly than diploids but for a longer period, and, on the whole, plants with the largest rosettes developed the biggest roots. Sibling tetraploids exhibited less deviation from the mean than randomized plants in such characters as number, size; and shape of leaves, production of heads, and weight of roots. Leaf characteristics provided the clearest evidence of an inheritance mechanism. The data on root weight were less conclusive.

ISSN:1923-4287    

DOI:10.1139/cjr46c-011

出版商:NRC Research Press    

年代:1946

数据来源: NRC