摘要:

Seed cones inTsuga heterophylla(Raf.) Sarg. are found at the tips of distal lateral branches and form as a result of the transition of a previously vegetative apex. Pollen cones may be formed similarly and are then found at the tips of less-vigorous proximal branches but more commonly they develop from newly initiated axillary buds on short proximal shoots. In all cases, apices undergo transition to the reproductive state after a period of bud-scale initiation. Some apices initiate many bud scales, then either initiate leaves or undergo transition to a seed-cone apex in July. Other apices initiate fewer bud scales, then late in June undergo transition to a pollen-cone apex. Transition to a reproductive apex is marked by an increase in mitotic activity and apical size and loss of the vegetative pattern of zonation. Zonation reappears during the slower period of late bract and microsporophyll initiation but is not as prominent as it was in vegetative apices. In seed-cone buds, all bracts, ovuliferous scales, and megaspore mother cells are formed before dormancy. In pollen-cone buds all microsporophylls and microsporangia are initiated before dormancy and pollen mother cells begin meiosis and remain in the diffuse diplotene stage during dormancy. Pollen- and seed-cone buds become dormant in December. The time of cone initiation and sexuality of cones may be influenced by day length. The pattern of reproduction in western hemlock is compared in some respects with that of other conifers.

ISSN:0008-4026    

DOI:10.1139/b74-037

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Mung bean (Phaseolus aureusRoxb.) cuttings were used to study enzyme changes during root initiation. Gel electrophoresis of protein extracts from the hypocotyl tissue revealed the emergence of a major protein complex during the early stages of root initiation. This protein fraction showed multiple enzymatic function including polyphenol oxidase, peroxidase, and indole-3-acetic acid oxidase. Two root-promoting substances, indoleacetic acid (IAA) and catechol, enhanced the activity of the protein complex during the early stages of root initiation. The significance of this isozymic activity with respect to the modulation of rooting promoting factors is discussed.

ISSN:0008-4026    

DOI:10.1139/b74-038

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Primordial bud formation inCoprinus lagopusis strictly light dependent, but onlyexposure to light is required. However, continued exposure to light is mandatory for further development and hymenium differentiation into a mature basidiocarp. Without light, the stipe of the primordial bud elongates as if the basidiocarp is maturing and the primordial bud eventually aborts. The optimum light intensity is less than 1 ft-c at a wavelength of 410–450 nm. It is possible that cap and stipe are initiated by the same stimulus, but further development of each is under different controls. The former is light dependent whereas the latter is not.The primordial bud development was studied at daily intervals for 3 days until meiosis started and their structural differentiations were studied by paraffin section and squash preparations. The cap of the primordial bud has three zones: the veil, the hymenium, and the stipe. The veil cells are large and multinucleate and lack clamp connections. The stipe includes a central column of dikaryotic hyphae and a cortex of giant multinucleate cells. The hymenium contains only dikaryotic hyphae, which later develop into basidia, cystidia, and medullar cells. The gill development is started by structural organization of dikaryotic hyphae into dome-shaped ridges, which is followed by disintegration of cells surrounding these ridges to form gills. The gill expansion is also light dependent.When the primordial buds were exposed to light, there was a thrust of mitotic activity. Mitotic metaphase, anaphase, and telophase configurations were clearly demonstrated.

ISSN:0008-4026    

DOI:10.1139/b74-039

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Twenty-seven flavonols were isolated from entire plants ofTellima grandiflora(Pursh) Dougl. Kaempferol and quercetin occurred as their 3-glucosides, 3-galactosides, 3-arabinosides, 3-rutinosides, and 4′-glucosides. Myricetin occurred as the 3-glucoside and 3-galactoside. Twelve acylated derivatives based upon the 3-glucosides and 3-galactosides of the three flavonols were isolated but not completely characterized. The flavonoid glycoside chemistry of Saxifragaceae s.l. was reviewed.

ISSN:0008-4026    

DOI:10.1139/b74-040

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Ultrastructure studies of the pollen grains ofOpuntia polyacanthareveal an elaborately sculptured ektexine but no endexine. The mature pollen cytoplasm is non-vacuolated, and contains plastids, starch granules, lipids, endoplasmic reticulum (ER), and relatively few other recognizable structures. Membranes and inclusions taken to be plasmalemmasomes were observed in the intine. Invaginations of the plasma membrane were also observed.

ISSN:0008-4026    

DOI:10.1139/b74-041

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Chromosome numbers and meiotic behavior are reported for 126 collections of grasses representing 50 genera and 111 species. First counts are given for the generaLeptothrium, n = 10, andCryptochloa, 2n = 22 (somatic count). First chromosome counts are given for the following 25 species:Aristida recurvata, n = 11;Axonopus laxus, n = 20;Chloris mollis, n = 20;Chusquea longifolia, n = 20;Cryptochloa concinna, 2n = 22;Digitaria abyssinica, n = 18;Eragrostis airoides, n = 36;E. guianensis, n = 10;Eriochloa boxiana, n = 18;Gymnopogon foliosus, n = 10;Leptothrium rigidum, n = 10;Luziola pittieri, n = 12;L. spruceana, n = 24;Otachyrium inaequale, n = 10;Panicum cayennense, n = 27;P. chloroticiun, n = 18;P. schiffneri, n = 18;Pappophorum pappiferum, n = 30;Paspalum apiculatum, n = 10;P. arundinaceum, n = 30;P. contractum, n = 9;P. coryphaeum, n = 30;P. trachycoleon, n = 20;Setaria barbata, n = 27; andTrisetum foliosum, n = 28. Counts that differ from previously reported counts are given for the following 15 species:Axonopus chrysoblepharis, n = 10;Cenchrus brownii, n = 34;Digitaria horizontalis, n = 9, 27;Echinolaena gracilis, n = 10;Euclasta condylotricha, n = 10;Hyperthelia dissoluta, n = ca. 30;Ischaemum guianense, n = 18;Microchloa indica, n = 12;Paspalum candidum, n = 10;P. melanospermum, n = 20;P. prostratum, n = 10;Rhytachne rottboellioides, n = 16;Setaria paniculifera, n = 16;Sorghastrum incompletum, n = 20; andThrasya petrosa, n = 30. Changes in nomenclature are indicated forDigitariaspecies whose chromosome numbers were reported in our earlier publications.

ISSN:0008-4026    

DOI:10.1139/b74-042

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The net assimilation capacity of long and short shoot leaves ofGinkgo bilobaL. was measured and found to be similar in both groups of leaves. Anatomical investigation indicated that a previous report of differences in the palisade mesophylls of the two groups of leaves was unfounded, and this is reflected by the similarities in their net assimilation capabilities.

ISSN:0008-4026    

DOI:10.1139/b74-043

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Eight species ofAmanitacollected in Nova Scotia are compared macroscopically and microscopically with previously published descriptions and some new data are given. Of these eight, five species and one variety are recorded from the province for the first time, and two (Amanita macrosporaandA. solaniolens) are described as new species.

ISSN:0008-4026    

DOI:10.1139/b74-044

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

An arctic–alpineCarexsmut, described by Rostrup asTilletia arcticaand later assigned toCintractiaandUstilago, has completely external sori and has no relationship to any of these genera. It is assigned toOrphanomycesgen. nov. (Ustilaginaceae). A second species,O. vankyisp. nov., is described from the mountains of Transylvania onCarex acutiformis.

ISSN:0008-4026    

DOI:10.1139/b74-045

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The distribution of xylem and phloem transfer cells in the node of bamboo has been described. Bundles supplying the leaf sheath contain numerous xylem transfer cells while those supplying the internode above the node and the axillary bud contain groups of phloem transfer cells which appear as swollen or knotted regions in the node. The significance of the presence of transfer cells in the nodes and the possible function of them are discussed.

ISSN:0008-4026    

DOI:10.1139/b74-046

出版商:NRC Research Press    

年代:1974

数据来源: NRC