摘要:

James, LoisE. (Whittier Coll., Whittier, Calif.), and DonaldW. Kyhos.The nature of the fleshy shoot of Allenrolfea and allied genera.Amer. Jour. Bot. 48(2): 101–108. Illus. 1961.—A number of genera of the Chenopodiaceae are characterized by what have been called fleshy internodes which make them appear jointed. The fleshy tissue comprises on the average the outer ⅔ of what superficially appears to be the stem. This fleshy tissue contains a vascular network which is continuous with and similar to the vascular network in what has commonly been called the scalelike leaf. The problem is whether this fleshy vascularized tissue is the result of a downward prolongation of the base of the leaf or whether it is actually the true cortex of the stem. The present authors have found thatAllenrolfeais uniquely suited to solving the problem of the so‐called fleshy internodes of these allied genera. The origin and development of the fleshy tissue indicate it to be foliar. This conclusion is further substantiated by the shape of the fleshy tissue, its phyllotactic arrangement, the extent of the palisade tissue and underlying vascular network, the pattern of branching of the leaf traces, and the effect of secondary thickening and suberization.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11610.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Davis, EdwardL. (U. Massachusetts, Amherst.)Medullary bundles in the genus Dahlia and their possible origin.Amer. Jour. Bot. 48(2): 108–113. Illus. 1961.—The system of medullary bundles which extends throughout the stem and into the leaves and branches inD. lehmanniis described. It is suggested that this system may have arisen from leaf traces and that the condition inD. scapigeravar.scapigeraf.merckiiandD. coccinea, in which leaf traces fail to develop secondary tissue while adjacent bundles are increasing in diameter, may represent the incipient stage of development of medullary bundles within the genus. The correspondence between the occurrence of medullary bundles and the sectional division of the genus on taxonomic grounds by Sherff is noted.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11611.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Uhl, CharlesH. (Cornell U., Ithaca, New York.)Chromosomes of the Sempervivoideae (Crassulaceae).Amer. Jour. Bot. 48(2): 114–123. Illus. 1961.—Chromosome numbers are reported for 207 collections representing 68 of the ca. 95 species in this subfamily. Basic numbers are 16, 17, 18, and 19 inSempervivum, Section Sempervivum (10 species, with many tetraploids and one hexaploid); 19 inSempervivum, Section Jovisbarba (5 species, all diploid); 15 inAichryson(9 species, including 1 aneuploid, 1 tetraploid, and 1 aneutetraploid); and strictly 18 inAeonium(31 species, including 4 wholly and 1 partly tetraploid),Greenovia(3 species, 1 partly tetraploid), andMonanthes(10 species, including 2 wholly and 1 partly tetraploid). The cytological evidence appears decisive in ranking several species of disputed generic position definitely withAichrysonrather than withAeonium.Possible relationships between various Canarian genera and certain North African species often classed inSedumare discussed briefly in the light of the scanty morphological and cytological evidence. It is suggested that both these groups may be descended from the same ancestors that were widespread in North Africa before the deserts developed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11612.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Olive, L. S., and A. A. Fantini. (Columbia U., New York, N. Y.)A new, heterothallic species of Sordaria.Amer. Jour. Bot. 48(2): 124–128. Illus. 1961.—S. brevicollis, sp. nov., was isolated from zebra dung from the New York Zoological Park. It is the only species of the genus that has been found to be heterothallic and to have microconidia. The latter function readily in fertilization. Heterothallism is controlled by a single allelic pair of compatibility factors located about 14.2 crossover units from the centromere. Incomplete mating reactions involving this species,Gelasinospora autosteira, andNeurospora crassaindicate relationships among these 3 genera.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11613.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Dehnel, GeorgeS. (U. Missouri, Columbia.)Abnormal stomatal development in foliage leaves of Begonia aridicaulis.Amer. Jour. Bot. 48(2): 129–133. Illus. 1961.—The results of 2 types of aberrant stomatal development in abaxial epidermis of normal laminae ofB. aridicaulisare discussed and illustrated. The more common is a so‐calledpersistent stomatal initialthat is an essentially circular cell (in face view) with chloroplasts and a wall of uniform thickness. The other type of anomalous development yields asingle guard cell, which possesses chloroplasts, differential wall thickening, rarely a pore, and a form characteristic of a normally paired guard cell. Both types of cells may either be isolated or occur variably in close relationship to normal stomata.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11614.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Riley, H. P., and T. R. Bryant. (U. Kentucky, Lexington.)The separation of nine species of the Iridaceae by paper chromatography.Amer. Jour. Bot. 48(2): 133–137, Illus. 1961.—Chromatograms were made from small pieces of the root tip of 9 species of 4 genera of the Iridaceae. Under ultraviolet light, the patterns ofWatsonia arderneiandW. vanderspuyaewere almost identical which suggests that they are closely related species. On the basis of chromatographic patterns,W. fourcadeiapparently is not so closely related to them but is rather closely related toW. wilmaniae; W. pyramidataandW. wordsworthianaare less closely related to the other species. The patterns ofDietes grandiflora, Babiana bainesiiandSparaxis aureumare strikingly different from one another and from those of the species ofWatsonia.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11615.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Avers, CharlotteJ. (Douglass Coll., Rutgers—The State University, New Brunswick, N. J.)Histochemical localization of enzyme activities in root meristem cells.Amer. Jour. Bot. 48(2): 137–143. Illus. 1961,—Particle counts were made in epidermal cells of the root meristem of 2 grasses after exposure of living seedlings to various substrates involved in dehydrogenation reactions. Hydrolytic enzyme activities also were recorded for 1 of these species. The mean number of particles stained with Janus green B was about 90 for each species, but significantly lower counts were obtained in all the dehydrogenase tests. With lactate, pyruvate, glutamate, citrate, and isocitrate as substrates,Phleumcells showed about 25% of the Janus green count, whilePanicumcells were about 33% active. These substrates are known to be oxidized by DPN‐linked enzymes. The succinic dehydrogenase counts were about 50% of the Janus green total, and 60–70% particle activity was recorded with hexose‐phosphate substrates which are probably oxidized in TPN‐mediated reactions. InPhleum, particulate activity occurred in the adenosine triphosphatase and aryl sulfatase tests, but a non‐particulate distribution characterized 5‐nucleotidase activity. The particle counts in the ATPase tests were not significantly different from the Janus green counts, but the 85% particle activity in the aryl sulfatase tests was significantly lower than the Janus green results. These intracellular distributions were compared with those obtained by various authors using biochemical and histochemical techniques and were found to be in close agreement. It was suggested that the evidence indicated intracellular differentiation of at least one kind of cellular organelle, which in all probability was mitochondria.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11616.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Browne, EdwardT., Jr. (U. of Kentucky, Lexington.)Morphological studies in Aletris. I. Development of the ovule, megaspores and megagametophyte of A. aurea and their connection with the systematics of the genus.Amer. Jour. Bot. 48(2): 143–147. Illus. 1961.—Development in a North American species of this variously classified genus has shown great similarity with the development in several genera of Hutchinson's Liliaceae‐Narthecieae:Pleea, Tofieldia, Nanheciumand∗∗∗Metaparthecium.The ovules are anatropous, bitegmic, crassinucellate and arranged in 4 rows in each locule of the tricarpellate pistil. There is a hypostase and an obturator. The primary archesporial cell is hypodermal. This undergoes a division to form a wall cell and the megaspore parent cell (MPC). The megaspores usually have a linear arrangement although occasionally a T‐shaped tetrad may be formed. Most frequently the chalazal megaspore functions, but rarely the one adjacent to it may enlarge instead. Megagametophyte development is of thePolygonumtype. A characteristic narrowed chalazal constriction is formed during the development of the megagametophyte. It is recommended on the basis of this information thatAletrisbe classified with the genera of the Liliaceae‐Narthecieae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11617.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Goodwin, DonnaC. (State U. Iowa, Iowa City.)Morphogenesis of the sporangium of Comatricha.Amer. Jour. Bot. 48(2): 148–154. IIlus. 1961.—Three species of the myxomycete genus,Comatricha, were studied:Comatricha nigra, C. fimbriata, and C.elegans.The sporangia developed on living bark ofUlmus americanain moist chamber. The hypothallus is formed under the homogeneous protoplasmic mass of the sporangial initial. The fibrous threads of the hypothallus bend upward, lengthening at the apices to become the fibers of the stalk and columella. The undifferentiated protoplasm is carried upward as the stalk elongates. When the columella has attained its mature height, threads bend out from the columella and grow toward the periphery of the sporangium. These threads form the capillitium. Simultaneous with the appearance of the capillitial initials, the peridium, a delicate membrane, forms. After the capillitium is mature, the protoplast cleaves into many cells, the future spores. The peridium evanesces early in the stage of spore maturation. Cellulose is present in the stalk, capillitium, and spore walls but is not found in the peridium or hypothallus. The capillitium of these species follows a developmental pattern designated as the “Comatricha‐type” by Ross (1957) from a study ofComatricha typhoides.The taxonomic implications of the sporangial developmental pattern are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11618.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Miller, J. H. (Yale U., New Haven, Conn.), and P. M. Miller.The effect of different light conditions and sucrose on the growth and development of the gametophyte of the fern, Onoclea sensibilis.Amer. Jour. Bot. 48(2): 154–159. Illus. 1961.—Gametophytes grow rapidly under the highest intensity white fluorescent light used, 400 ft.‐c. Growth is correspondingly less at 220 and 28 ft.‐c., and at the lowest light intensity the gametophytes are markedly longer than wide. One percent sucrose added to the medium reverses the growth limitation imposed by low light intensity and produces a morphology comparable to that found under higher intensities. Sucrose does not sustain heterotrophic growth in total darkness, but permits growth if the gametophytes are given low dosages of red light. The effect of red light is reversible by far‐red illumination.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11619.x

出版商:Wiley    

年代:1961

数据来源: WILEY