摘要:

A survey of over 30 species ofAsterand 61 species in other genera of Astereae indicates that the somewhat flattened style branches of perfect disk florets characteristically unfold and spread in a pronate, rather than a supinate manner. While not exhibited in all genera(BaccharisandConyzaare among the exceptions), this phenomenon appears to be restricted to and, therefore, diagnostic for the tribe. The slender style branches of pistillate ray florets display the supinate expansion which is regularly observed in other tribes of Compositae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11810.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Three different types of outgrowths develop from epidermal cells of excised juvenile leaves ofMicrogramma vacciniifolia:aposporous gametophytes, intermediates, and regenerated sporophytic plantlets. The gametophytes and intermediates arise from derivatives of epidermal cell divisions which are developed to the exterior of the leaf surface, whereas the sporophytic regenerants originate from derivatives produced by cell divisions to the interior of the leaf. Anatomical observations of excised leaves grown in vitro demonstrate that only the epidermal cells are stimulated to divide and give rise to the various types of outgrowths. Incorporation of tritiated thymidine by the nuclei of leaf epidermal cells gives further evidence for the metabolic activity of these cells.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11811.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The genusCordyhmthushas considerable diversity in its inflorescences while the other genera of tribe Rhinantheae (Scrophulariaceae) uniformly have racemes or spikes. Four distinct inflorescence types are recognized and their homologies and evolutionary history are postulated. Thus it is suggested that the basic florescence type, the elongated spike (Type I), has undergone evolutionary reduction to a few‐flowered spike and ultimately to a single‐flowered florescence (Type II). Further evolution involving processes of compaction and clustering of the single‐flowered florescences has resulted in glomerulate clusters (Type III) and spiciform clusters (Type IV). Knowledge of inflorescence homologies and distribution of the four inflorescence types in the genus has been of considerable aid in formulating a new infrageneric classification. Using evidence primarily from inflorescence, floral, and seed morphology, as well as from geographical distribution and ecology, a classification is proposed establishing three subgenera, namely subg.Dicranostegia, subg.Hemistegia, and subg.Cordylanthus, the last with three sections, sect.Cordylanthus, sect.Anisocheila, and sect.Ramosi.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11812.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Experiments were performed to determine the effects of simulated acid rain onPhaseolus vulgarisL. AtpH values below 3, plants exhibited a failure to attain normal height, had necrotic and wrinkled leaves, excessive and adventitious budding, and premature abscission of primary leaves. Histologically, leaves had smaller cells, less intercellular space, and smaller starch granules within the chloroplasts. Respiration rates of the treated plants increased only slightly at lowpH values. Apparent rates of photosynthesis, however, increased dramatically. Both carbohydrate production and root biomass were reduced by lowpH treatments, and application of Congo red indicator to the acid‐treated leaf tissue showed that the cell contents were acidified to apH of below 4.0.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11813.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Paired initiation of stamens and carpels on the apical meristem and bilateral symmetry of the flower are shown to prevail inSaururus cernuus.The carpels are initiated in two successive pairs of two members each, in a decussate arrangement. The floral apex shows plastochronic expansion in area between initiation of the last stamens and the first carpels, and also a less marked expansion between the two pairs of carpels. Vascularization appears to be whorled, with all carpels being supplied at once and at the same level. The vasculature of the flower is basically four‐stranded, such that each strand supplies a carpel and one, two, or three stamens. Carpels of a flower become unequal in size and level of attachment through post‐initiatory changes; these changes obscure the paired, decussate sequence of initiation. Phylogenetic conclusions aboutSaururusbased on its supposedly spiral initiation of parts are in need of reexamination;Saururusexhibits a highly specialized pattern of paired organ initiation which is bilaterally organized, rather than radial and helical as in most primitive angiosperms. Vasculature of the flower involves divergence of appendage traces at approximately the same time for all stamens, and simultaneously for all carpels, contrary to previous reports that divergence is helical or spiral in succession. All carpel bundles diverge from sympodia which supply at least one stamen, also contrary to previous descriptions.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11814.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Water soluble seed proteins from 69 populations representing seven species ofChenopodiumwere separated electrophoretically. Very little or no intraspecific variation was detected. The use of seed proteins as taxonomic characters was evaluated and compared to data from flavonoid chemistry. Seed proteins are of value in distinguishingC. atrovirensandC. leptophyllum, something which could not be done with flavonoids. Proteins and flavonoid data demonstrated thatC. hiansandC. leptophyllumare distinct. An analysis of storage proteins failed to differentiateC. desiccatumfromC. atrovirensandC. pratericolaeven though the species are distinct in flavonoids and other characters.Chenopodium atrovirensandC. pratericolaproduce similar or identical seed proteins, just as they are identical in flavonoids. Seed proteins indicated that plants referable toC. incognitumrepresent two biological entities, one apparently a minor morphological variant ofC. atrovirensand the other conspecific with C.hians.The same interpretation had been given on the basis of flavonoid chemistry. The protein data suggest a close relationship betweenC. subglabrumon the one hand andC. atrovirensand/orC. desiccatumon the other.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11815.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

A neotype specimen is designated forR. formosaand a representative specimen forR. sanguined, thus securing taxonomic concepts for these names. Two very similar taxa are proposed as new:R. eosanguinea, which differs fromR. sanguineachiefly in exhibiting clamp connections, andR. neoformosawhich differs fromR. formosachiefly in the absence of clamps. The subject of mimic taxa is briefly discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11816.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Effects of hybridization on sesquiterpene lactones inXanthium strumariumwere studied for clues to the relationship of Old and New World populations. In crosses between indigenous Asiatic plants in the “strumarium” morphological complex and various American complexes that produce xanthinin as a major sesquiterpene lactone, the F1hybrids contained xanthinin and the related compounds, xanthanol, xanthatin, and xanthinosin. In other crosses with various American complexes that produce xanthumin, the stereoisomer of xanthinin, the F1hybrids contained xanthinin and xanthumin as well as xanthinin‐related compounds and their stereoisomers, xanthumanol, deacetoxylxanthumin, and tomentosin. The Asiatic plants of “strumarium” from Hong Kong involved in the crosses produce approximately equal percentages of xanthinin, xanthatin and xanthinosin, but those from India contain only xanthinosin. The putative introduction of the American morphological complex, “chinense,” contains xanthumin as the major component but shows chemical diversity that indicates genes derived from the indigenous “strumarium” complex.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11817.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Gametophore induction in the mossPylaisiella selwyniibyAgrobacteriuin tumefaciensstrain B6 does not occur in parabiotic chambers when the moss and bacterium are separated by filters of 0.22 μm pore diameter. The combination of moss plus bacteria which gives increased gametophore formation also had no effect on sterile moss plants separated from the mixture by these filters. Heat‐killed B6 cells inhibit gametophore induction by viable B6 cells when added prior to or with the viable bacteria but not when added 6 or more hr later. The concentration dependence of both gametophore induction by viable B6 cells and inhibition of this process by heat‐killed B6 cells appears linear, suggesting that each response may require only one particle. Gametophore induction byAgrobacterium, therefore, requires physical contact comparable to the bacteria‐site attachment step demonstrated essential for tumor induction in higher plants and shows similar concentration dependence. The size of the moss and the absence of a wound requirement for this response makes theAgrobacterium‐moss system particularly advantageous for further resolution of the site attachment step inAgrobacteriumtumorigenesis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11818.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Distribution of coagulation of young shoot homogenates was surveyed in 430 accessions from the orange subfamily Aurantioideae. Representatives of four genera available for study(Clausena, Glycosmis, Aegle, Feronia)were coagulating taxa. The genusCitrusincluded both coagulating and noncoagulating taxa. Nineteen genera(Murraya, Merillia, Pamburus, Paramignya, Triphasia, Aeglopsis, Afraegle, Balsamocitrus, Feroniella, Swinglea, Atalantia, Citropsis, Hesperethusa, Pleiospermium, Severinia, Clymenia, Eremocitrus, Poncirus, Fortunella)were noncoagulating. The status of eight genera(Micromelum, Wenzelia, Monanthocitrus, Oxanthera, Merope, Luvunga, Burkillanthus, Limnocitrus)is not known. Homogenized tissue from coagulating taxa turned into a paste while tissue from noncoagulating taxa was thin and juicy. Coagulation did not take place when thepH of the grinding medium was 11 or higher but it would occur if thepH was lowered. Homogenates of noncoagulating taxa become coagulated belowpH 5.2–5.3, but remained noncoagulating above this. Noncoagulating taxa contained an unidentified substance which inhibited coagulation of tissue from coagulating taxa. The mechanism of coagulation and noncoagulaton is not presently known. The significance of coagulation and its absence as a taxonomic and genetic marker is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11819.x

出版商:Wiley    

年代:1976

数据来源: WILEY