摘要:

AllVancouveriaspecies are habitual myrmecochores of theViola odoratatype. The anatropous, bitegmic seed develops an unusual elaiosome in the form of a large, empty, folded and lobed sac of epidermal tissue. The thin‐walled assimilating capsule dehisces along an oblique weak zone that probably represents the suture between two fused and unequal carpels. InV. hexandrathe capsule opens early to expose immature assimilating seeds. Decurved pedicels, down‐turned fruits, and weak funiculi produce tachyspory. The relatedEpimedium, Jeffersonia, andPlagiorhegmahave appendaged seeds and other possible myrmecochorous features resembling those ofVancouveria. Myrmecochory was probably established in the early or middle Tertiary period. TheVancouveria‐Epimediumcomplex indicates that enormous plant migrations may be accomplished by means of ants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10069.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

The ultrastructure of early stages in embryogenesis in barley was examined. Post‐fertilization shrinkage does not occur. Plasmodesmata were not observed in cell walls of the zygote and outer cell walls of embryos. There is little evidence of cellular specialization in earliest embryonic stages, and planes of cell division tend to be irregular although a pattern of cell disposition characteristic of some grass embryos can be discerned. The embryo appears polarized after 2–3 division cycles, but no evolving of dorsiventrality occurs during this period. A basal supensor cell “anchors” the embryo during early embryogenesis, but by about five division cycles the embryo loses its attachment to the nucellus and is completely surrounded by endosperm. An increase in number of ribosomes and mitochondria takes place during early embryogenesis, and mitochondrial dimensions are reduced. A shift in vacuole distribution occurs.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10070.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

The transpiration and stomatal behavior of blight‐susceptible and blight‐resistant oats(Avena sativaL.) were followed after treatment with victorin, the host‐specific toxin ofHelminthosporium victoriae, and fusicoccin, the toxin produced byFusicoccum amygdali. Victorin, at 0.012 units/ml and greater, significantly decreased the transpiration of the blight‐susceptible variety in 3 hr, but had no effect on the transpiration of the blight‐resistant variety. The stomatal resistance, measured with a ventilated diffusion porometer, showed that the decrease in transpiration was caused by stomatal closure; the greater the concentration of victorin the earlier the stomata closed. At high concentrations of victorin the stomata reopened in the blight‐susceptible variety, and partial stomatal closure was observed in the resistant variety. Inactivated toxin had no effect on the stomata of either oat variety. When fusicoccin and victorin were compared under the same environmental conditions, victorin closed the stomata of the blight‐susceptible leaves, whereas fusicoccin opened the stomata in both the blight‐susceptible and resistant leaves. It is concluded that the two toxins differ in their effects on the guard cells; their possible modes of action are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10071.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

The effect of 4‐amino,3,5,6‐trichloropicolinic acid (picloram) on transport from leaves to the roots was studied using young bean(Phaseolus vulgarisL.), mesquite(Prosopis julifloravar.velutina(Woot.) Sarg.), and huisache (Acacia farnesiana(L) Willd.) plants. The only picloram treatments which were effective in enhancing transport of14C‐assimilate or14C‐picloram to the roots were those made to the shoots or roots one day or more before application of the label to the shoots. The enhancement of transport was not evident when un‐labeled picloram or 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), or both, were applied at the same time as the14C‐label. Enhancement of transport was to the more mature stem or root tissues. Inorganic nitrogen applied to nitrogen‐deficient bean plants also increased transport of14C‐assimilate to the roots, especially the rate.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10072.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

The barley mutantseceriferum‐g, which have wax deficiencies in several organs, show an abnormal stomatal development as a pleiotropic effect. The main abnormalities are double and triple stomatal complexes. Minor alterations are present as extra cells that alter the normal sequence of the stomatal row and abnormal subsidiary cells that are either larger, smaller, or displaced from their normal position. These characteristics are present in the 12 independently isolated mutants of theglocus, but could not be found in any of the othereceriferummutants studied. The morphogenetic origin and a developmental sequence for the abnormalities are postulated.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10073.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Morphological intermediacy betweenTsuga heterophyllaandTsuga mertensianahas stimulated controversy concerning the relationship between these two hemlock species and has led to wide acceptance of hybridization as a causative factor of intermediate forms in areas of distributional overlap. In this study, comparative’ chemical analyses were used to test the theory of hybrid derivation of intermediates. Chromatographic analyses were further applied to the phylogenetic ranking of several North American and Asian species ofTsugaand to the examination of the hypothesis thatTsuga mertensianais a derivative of intergeneric hybridization involvingTsuga heterophyllaandPicea sitchensis. Chromatographic data derived from extensive sampling in the western Cascades of Washington led me to conclude that hybridization ofTsuga heterophyllaandT. mertensianais a possible but rare phenomenon and is not necessarily indicated by morphological intermediacy. Phylogenetically both of these species are typical representatives ofTsugaand are distinct from species ofPicea. There is, however, some support for the derivation ofTsuga mertensianaby intergeneric hybridization.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10074.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Petal extracts ofGossypiumwere analyzed chromatographically to determine if flavonoid constituents are modified by different environments. In the initial phase, fourteen inbred stocks from four species were grown in a plot that was replicated in five different localities ranging from the Mojave Desert to Raleigh, North Carolina. Petal samples were collected from each stock at each site, and chromatograms developed from these samples looked highly similar regardless of the locality of the growing site. In the second phase, two stocks were phytotron grown under a series of regimes in which daylength, temperature, and mineral nutrition were varied. Each stock showed very little floral flavonoid variation despite the growing conditions. A chromatographic survey of leaf extracts from these same phytotrongrown plants showed them to be much more variable. In cotton, flower petal constituents appear to be less variable than leaf constituents. The chemotaxonomic significance of these results are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10075.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Ascosporic cultures were obtained from spore shoots ofHymenoscyphus caudatusgrowing abundantly on leaves ofAcer rubrum. In determining the proper medium, light, and temperature for growth, anIdriellaconidial stage was discovered for this fungus. Attempts to induce apothecia to develop under artificial conditions proved unsuccessful.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10076.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

Invagination of the plasma membrane in plant cells forms peripheral or endocytic structures which often contain a complement of membrane‐bound vesicles. These structures, or secondary vacuoles, move with the streaming cytoplasm although their velocities are somewhat slower than that for the various organelles within the cytoplasm. They glide over the nucleus or flow from the peripheral cytoplasm onto a transvacuolar strand and continue unabated along the length of a strand. These structures may detach from the plasma membrane as sacs to become positioned in the cytoplasm directly under the tonoplast and project into the primary vacuole. Some endocytic vacuoles may separate from the peripheral cytoplasm and remain free within the primary vacuole; subsequently they can re‐associate with the cytoplasm. While the content and function of these vacuoles are yet to be determined, indirect evidence indicates that they are pinocytic in character since the content of an invagination is confined to the sac upon its detachment from the plasma membrane and is subsequently transported throughout the cell by cyclosis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10077.x

出版商:Wiley    

年代:1972

数据来源: WILEY

摘要:

A new genusStrotheria, containing the single speciesS. gypsophila, has been described from a locality in north‐central Mexico. It is relatively common on gypsum soils at this site, along with several other gypseous endemics. The genus is presumably related toDyssodiabut differs in having succulent, non‐glandular foliage and only four florets per head. Its chromosome number was determined asn= 8.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1972.tb10078.x

出版商:Wiley    

年代:1972

数据来源: WILEY