摘要:

Although the two species inBarbaceniopsis—B. boliviensisandB. vargasiana—have in common many features which support their inclusion in one genus, there are also obvious differences in the depth of leaf furrows, absence of hairs inB. vargasiana, and type of girder sclerenchyma in the leaf. The presence of vessels in the leaf has been demonstrated. The frequent observation that the roots cling tightly only to stems ofVelloziaspecies is shown to be characteristic of the family. A comparison of the three genera clearly indicates that there are obvious anatomical characters which help to distinguishBarbaceniopsisandBarbaceniafromVellozia. Although it is not suggested thatBarbaceniopsisbe reduced to synonymy, there can be no doubt that it is very closely associated withBarbacenia.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07393.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The structure and ontogeny of the calyx and corolla ofDowningia bacigalupiiWeiler (Campanulaceae; Lobelioideae) were investigated for the purpose of comparing perianth development with previous observations on the floral bract, as well as elucidating the mechanism of development of the zygomorphic, sympetalous corolla. Sepals are uni‐traced with a palmate, reticulate venation. They have basal and apical hydathodes, as well as storage tracheids. Sepals show a reduction in size, venation and hydathode number when compared to the bract. The pentamerous, zygomorphic corolla is bilabiate, consisting of a three‐lobed adaxial lip and a two‐lobed abaxial lip connected by a short tubular region. The constituent petal lobes are also uni‐traced and have a reticulate venation, resembling that of the sepal and bract, but lack storage tracheids and hydathodes. Sepals arise in an adaxial to abaxial succession and are initiated in the outer corpus layer of the floral apex. Expansion of the floral apex follows and is accompanied by the establishment of a second tunica layer. Sepals undergo apical, marginal, and intercalary growth accompanied by acropetal differentiation of procambium. The petals arise simultaneously and are initiated in the second tunica layer and the outer corpus cells. After initiation, the petals exhibit a period of apical and marginal growth followed by intercalary growth. Apical growth in petals is less protracted than in sepals, but plate meristem activity is more extensive. The free petal lobes become temporarily fused by an interlocking of marginal epidermal layers, but they separate at anthesis. Zonal growth beneath the originally free lobes forms the tube and lip regions of the sympetalous corolla. Zygomorphy is evident from the time of initiation of petals and is accentuated by later differential growth. Comparative observations of corolla ontogeny in autogamous species ofDoumingiaindicate that the reduced corollas in these taxa are derived by a simple process of neoteny.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07394.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Histological observations were made on normal and mutant strains of safflower in order to compare the development of the “fibrous” tissues among the various strains. The fibers of the vascular bundles of normal and F1's from crosses between normal and thin‐hull mutant types had well‐developed secondary cell walls, but they appeared reduced in mutant types. The anthers of all types showed a similar pattern of differentiation and maturation up to the final stages of tapetal breakdown when secondary walls and rib formations appeared in the connective regions and endothecial cells of the normal, striped and F1types. These formations were absent from the thin‐hull mutants. In both types dehiscence took place along a longitudinal fissure at the junction of the pollen sacs of one lobe of the anther. The anther flaps of normal types opened abruptly, thus effectively bringing the pollen into contact with the elongating style. Those of the mutants collapsed in place preventing the release of pollen. Hulls of the mutant strains were thin because cells were not sclerified during differentiation of the pericarp. Striped hulls resulted from the additional localization of secretory canals in the pericarp of the striped mutant.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07395.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Eleven flavonol glycosides and two anthocyanins, only one of which was previously identified, were isolated from the flower petals of okra,Hibiscus esculentusL. On the basis of chromatographic, spectral, and degradative evidence, the following structural assignments were made: quercetin 4′‐glucoside, quercetin 7‐glucoside, quercetin 5‐glucoside, quercetin 3‐diglucoside, quercetin 4′‐diglucoside, quercetin 3‐triglucoside, quercetin 5‐rhamnoglucoside, gossypetin 8‐glucoside, gossypetin 8‐rhamnoglucoside, gossypetin 3‐glucosido‐8‐rhamnoglucoside, cyanidin 4′‐glucoside, and cyanidin 3‐glucosido‐4′ glucoside. Some evidence was obtained of a pentahy‐droxy, monomethoxy‐flavone glycoside. The total flavonoid content in the red portion of the petal was 0.48% of fresh weight; that in the white portion was 2.51%. The two anthocyanins comprised 28.5% of the flavonoid content of the red flower but only a trace of the content of the white.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07396.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Physcomitrella patensis a monoecious, cleistocarpous moss which completes its life cycle under defined conditions in 7 to 8 weeks. Sexual reproduction is readily obtained by culturing gametophytes at 15 to 19 C. Mutants were induced by treatment of either spores or protonemal cells with ethyl methane sulfonate, N‐methyl‐N'‐nitro‐N‐nitrosoguanidine and X‐rays. Thiamine, para‐aminobenzoic acid, niacin and yeast extract auxotrophs were obtained. Growth response to various supplements was studied in the auxotrophic mutants. Five yellow mutants and two morphological mutants were induced. The chlorophyll content of the yellow mutants is reduced 35‐65% of wild type. The self‐sterile, para‐aminobenzoic acid‐dependent mutant was used as the archegonial parent in crosses with a yellow mutant and a morphological mutant. The self‐sterility of the para‐aminobenzoic acid‐requiring mutant appears to be pleiotropically related to the auxotrophic condition, since self‐sterility does not segregate from nutritional dependence in progeny of crosses. On the basis of tests with heterozygous diploids obtained by aposporous regeneration of capsule cells, two mutant alleles were shown to be recessive to their respective wild‐type alleles.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07397.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The primary vascular system of 23 species belonging to 18 genera of conifers with helical phyllotaxis has been investigated with the intent of determining the architecture of the system. Special attention has been given to nodal and subnodal relations of the vascular bundles. The vascular system seems to be composed solely of relatively discrete sympodia, that is, axial vascular bundles from which leaf traces branch unilaterally. Although the discreteness of the sympodia is not immediately apparent because of their undulation and lateral contacts with neighboring ones, close examination, including a statistical analysis of the tangential contacts, seems to reveal that each sympodium maintains its identity throughout. Although two traces may be apparent at nodal levels, the trace supply to a leaf originates, in all species, as a single bundle. An analysis is made of the relationship between the vasculature and the phyllotaxis. It is observed that the direction of trace divergence can be accurately predicted when the direction of the ontogenetic spiral, the angle of divergence of leaf traces, and the number of sympodia are known.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07398.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

This paper reports the results of a detailed comparative investigation of the primary vascular system of seven species of conifers characterized by opposite and whorled phyllotaxis. Three patterns, indicated as types I, II and III, are described. Type I is similar to the sympodial pattern of conifers with helical phyllotaxis. Type III is a reticulate system which results from a fusion of a pair of traces that form the vascular supply to each leaf. Each trace of the pair branches from a separate, adjacent sympodium, and the two traces diverge synchronously in opposite directions. Type II is intermediate between types I and III. It resembles type I in that the vascular supply to a leaf originates as a single trace, and it is similar to type III in that direction of trace divergence may be either sinistrorse or dextrorse. Four species were found to be characterized by both types II and III, the different types occurring in different shoot tips of the same individual. All three types were observed in one species. Where type II occurred in the same plant with either type I or type III, or in the one species in which all types occurred, some leaves were supplied by a trace originating singly, others by a trace originating as a pair of bundles. On the basis of a comparative analysis of the vascular patterns in conifers with helical, opposite and whorled phyllotaxis, including a correlation of the type of vascular pattern with other characters, it was concluded that the reticulate system is probably derived from the open system characteristic of conifers with helical leaf arrangement, that this type of vascular system is composed of sympodia, and that the origin of the vascular supply to a leaf as a single trace is the primitive condition in the Coniferales.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07399.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

This paper includes a survey of the nature of the primary vascular system in a large number of extinct gymnosperms and progymnosperms. The vascular system of a majority of these plants resembles closely that of living conifers, being characterized, except in the most primitive forms which are protostelic, by a eustele consisting of axial sympodial bundles from which leaf traces diverge. The vascular supply to a leaf originates as a single trace with very few exceptions. It is proposed that the eustele in the gymnosperms has evolved directly from the protostele by gradual medullation and concurrent separation of the peripheral conducting tissue into longitudinal sympodial bundles from which traces diverge radially. A subsequent modification results in divergence of traces in a tangential plane. The closed vascular system of conifers with opposite and whorled phyllotaxis, in which the vascular supply to a leaf originates as two traces which subsequently fuse, is considered to be derived from the open sympodial system characteristic of most gymnosperms. This hypothesis of stelar evolution is at variance with that of Jeffrey which suggests that the eustele of seed plants is derived by the lengthening and overlapping of leaf gaps in a siphonostele followed by further reduction in the resultant vascular bundles. This study suggests strongly that the “leaf gap” of conifers and other extant gymnosperms is not homologous with that of siphonostelic ferns and strengthens the validity of the view that Pterop‐sida is an unnatural group. It supports the position that gymnosperms have evolved from progymnosperms rather than from ferns, and the inclusion of ferns and gymnosperms in separate subdivisions or divisions.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07400.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The amphiploidNicotiana suaveolens×N. langsdorffii, which is genetically constituted to produce tumors spontaneously late in development, can be induced to form them in the early seedling stage by treatment of the apical meristem with kinetin and indoleacetic acid. Application of H3‐or C14‐labeled plant‐growth regulators resulted in most plants and notably with C14‐labeled indoleacetic acid in a significant increase in the rate of tumor production over growth‐regulator treatment alone. Endogenous radiation alone was shown to be tumefacient since radioactive nucleosides, tritiated water, and C14‐sodium carbonate also enhance tumorization.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07401.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Alfaroa mexicanais described as new. Certain aspects of the wood anatomy, inflorescence, pollen, staminate flower, and pistillate flower morphology are compared with previous findings on the three other species ofAlfaroaand representatives of the closely related genusEngelhardia.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07402.x

出版商:Wiley    

年代:1968

数据来源: WILEY