摘要:

Rapid (4 hr) auxin‐induced hyponastic curvature of primary leaves ofPhaseolus vulgarisis shown to depend on a positive increase in growth of the lower portion of the blade. The curvature involves laminar growth as well as vein growth and is not due to simple turgor changes. The response is sensitive to gravitational orientation, as inversion and horizontal rotation reduce the auxin‐induced curvature. The ethylene‐generating compound, 2‐chloroethylphosphonic acid, had no hyponastic effect on the leaves when applied to either the upper or lower surface and it inhibited auxin‐induced hyponasty. This inhibition was additive to that of inversion. Long‐term (24–48 hr) effects of 1 mM auxin depend on the surface of the leaf treated. Application to the upper surface results in epinasty, lower surface application in hyponasty, although the initial response in each case is a hyponastic curvature. A dorsi‐ventral auxin transport system and differential auxin sensitivity of upper and lower portions of the leaf blade are postulated to account for these responses.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11825.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The karyotype of A‐set and B‐chromosomes ofXanthisma texanumDC. are described in detail and measurements are given. The distribution of B‐chromosomes in stem tissue is described and the loss of B‐chromosomes from primary roots confirmed. The number of B‐chromosomes in pollen mother cells was constant within single inflorescence buds and in all buds throughout the flowering period. The behavior of one and two B‐chromosomes during meiosis is described in detail. During meiosis, B1's divided in 71% of the cases during anaphase II and in 29% of the cases during anaphase I. First anaphase division resulted in some lagging and elimination of B‐chromatids during second division. During anaphase I, B11's divided into chromosomes and in anaphase II these divided into chromatids in 95% of the cases. In the other 5 % non‐disjunction of the B‐chromosomes or chromatids and A‐set chromosome abnormalities occurred. Post meiotic preferential distribution during pollen mitosis resulting in a doubling of the number of B‐chromosomes passed to progeny via pollen occurred, but no doubling occurred in the female line. Crosses involving plants with two B‐chromosomes each yielded fewer plants with three B‐chromosomes than expected. Polyploidy is extremely rare in the species. The evolutionary significance of B‐chromosome behavior is discussed in relation to its origin and survival.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11826.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

A clear dichotomy exists in the genusRuellia, separating the blue from the red flowered species. Flavonoids differ in a qualitative rather than a quantitative way. Apigenin 7‐glucuronide and malvidin 3,5‐diglucoside are common to all the blue flowered species, whereas chalcononaringenin 2'‐glucoside (isosalipurposide) and pelargonidin 3,5‐diglucoside are shared by the red flowered ones.The blue flowered species are linked with the red via apigenin 7‐glucuronide and 3,5‐diglucosylation of their respective anthocyanins. Both groups are involved in flavonoid race formation. All examined species (and some populations within species) differ in flavonoid content. The patterns of variability displayed provide a basis upon which an evolutionary scheme is constructed. Genetic drift is hypothesized as the effector of race formation in the blue flowered group.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11827.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The breeding system, pollen tube development, and floral biology of three species ofEuphorbiasubgenusChamaesycefrom southeastern Arizona have been examined in field and greenhouse studies.E. albomarginatais entirely dependent on insect vectors for pollination and seed production,E. capitellatarequires insect visitors for maximum seed set but is capable of limited self‐pollination, andE. hyssopifoliais self‐pollinating and entirely independent of insect vectors. All three species are self‐compatible. The differences in reliance on insect vectors, diversity of insects and probable amount of outcrossing are related to differences in cyathial size and arrangement. The reproductive biology of the three species is similar to that described for other weedy plant taxa.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11828.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Primary shoot vasculature has been studied for 31 species of Pereskioideae and Opuntioideae from serial transections and stained, decorticated shoot tips. The eustele of all species is interpreted as consisting of sympodia, one for each orthostichy. A sympodium is composed of a vertically continuous axial bundle from which arise leaf‐ and areole‐trace bundles and, in many species, accessory bundles and bridges between axial bundles. Provascular strands for leaf traces and axial bundles are initiated acropetally and continuously within the residual meristem, but differentiation of procambium for areole traces and bridges is delayed until primordia form on axillary buds. The differentiation patterns of primary phloem and xylem are those typically found in other dicotyledons. In all species vascular supply for a leaf is principally derived from only one procambial bundle that arises from axial bundles, whereas traces from two axial bundles supply the axillary bud. Two structural patterns of primary vasculature are found in the species examined. In four species ofPereskiathat possess the least specialized wood in the stem, primary vascular systems are open, and leaf traces are mostly multipartite, arising from one axial bundle. In other Pereskioideae and Opuntioideae the vascular systems are closed through a bridge at each node that arises near the base of each leaf, and leaf traces are generally bipartite or single. Vascular systems inPereskiopsisare relatively simple as compared to the complex vasculature ofOpuntia, in which a vascular network is formed at each node by fusion of two sympodia and a leaf trace with areole traces and numerous accessory bundles. Variations in nodal structure correlate well with differences in external shoot morphology. Previous reports that cacti have typical 2‐trace, unilacunar nodal structure are probably incorrect. Pereskioideae and Opuntioideae have no additional medullary or cortical systems.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11829.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The developmental anatomy ofMirabilis jalapawas investigated during the first 90 days of growth. The primary thickening meristem (PTM) initially differentiates in the pericycle at the top of the cotyledonary node 18 days after germination, then basipetally in the pericycle through the hypocotyl. The PTM differentiates acropetally into the stem and in the pericycle of the primaiy root, commencing 22 days after germination. Endodermis is easily identifiable in hypocotyls as well as in primary roots because of Casparian thickenings in its cells. It has not been definitely identified in stems. There are three rings of primary vascular bundles in the stem. The PTM differentiates as segments of cambium in a layer of cells (probably in the pericycle) on an arc between vascular bundles of the outer bundle ring. Later, arcs of PTM differentiate externally to the phloem of each bundle. Each arc forms a connection between original segments of PTM lying on either side of each vascular bundle. Thus, the PTM becomes a continuous cylinder. The PTM differentiates in the pericycle outside vascular tissue in the hypocotyl and root. Differentiation of the PTM and the mode of secondary thickening is similar in plants exposed to short (8‐hr) and to long (18‐hr) photoperiods, but some differences were observed. The PTM differentiates closer to the stem apex in all plants over 18 clays of age growing vegetatively under long photoperiods. That is, the diffuse lateral meristem, in whose cells the PTM differentiates in young intemodes, is shorter in nearly all investigated plants growing in long photoperiods. The hypocotyl and base of the primary root of 40‐day‐old plants in short photoperiods were more enlarged than those of the same age plants in long photoperiods; but, at the end of 64 days, the hypocotyl and primaiy root base were larger in plants growing under short photoperiods. Thirty‐four days after seed germination, flower initiation occurs in plants exposed to short photoperiods. One hundred fifty days after seed germination, flowers differentiate on plants exposed to long photoperiods.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11830.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The spore wall ofDawsonia superbahas characteristics that, in many respects, are similar to those of other mosses except for the exine, which is layered inDawsonia.Imbibed spores have a well‐developed endoplasmic reticulum with dilated cisternae that are associated with vesicles at the periphery of the cell. Ribosomes on the surface of the vesicles suggest that many vesicles originate from the endoplasmic reticulum. Two types of protein storage bodies are observed: membrane bound protein bodies with a homogeneous matrix which gradually becomes vesicular, and densely stained and non‐membrane bound bodies consisting of crystalline arrays of fibrils. As in spores of higher plants, the protein reserves disappear during germination and may be converted to starch and other materials needed for development of the gametophyte.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11831.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The lens‐shaped, dorsiventral gametophytes ofOphioglossum crotalophoroidesare superficially different from the cylindrical gametophytes of other species ofOphioglossum.However, they have the same features as otherOphioglossumgametophytes (fundamentally axial organization, radially symmetrical apical meristem, radial distribution of gametangia) except that the cylindrical axis is reduced in length. Young sporophyte development is unique in the genus: all primary organs clearly arise from the embryo and develop simultaneously. The length of the life cycle ofO. crotalophoroiclesis considerably shorter than that of some other species in the Ophioglossaceae. A timetable for gametophyte and young sporophyte development is postulated. Spores germinate soon after they are released in the spring, and mature gametophytes develop by the next growing season. Fertilization occurs approximately one year after spore dispersal, and after two years, the photosynthetic first leaf of the young sporophyte emerges.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11832.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The morphological and chronological development of epicuticular waxes and their effects on the boundary layer of blue spruce needles were studied with a scanning electron microscope. Structural or crystalline‐like waxes develop first in the epistomatal chambers of needles in an expanding bud. However, as the needles emerge from the bud the structural waxes develop over the entire needle surface on glaucous foliage but are mainly restricted to the stomatal areas on non‐glaucous foliage. The epistomatal chambers are occluded with surface waxes as the needles emerge from the bud and they remained occluded. Structural waxes occlude the epistomatal chambers but as these waxes degrade the occlusion becomes amorphous in appearance. Structural waxes are degraded to an amorphous layer over the entire needle surface by weathering. Calculations reveal that the surface waxes of blue spruce are too small to have a significant effect on the boundary layer of the needle.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11833.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Absorption cytophotometry was used to measure nuclear Feulgen‐DNA content of myxamoebae and Plasmodia in seven heterothallic isolates ofDidymium iridis.Measurements of myxamoebal nuclei from clones of four isolates (Hon 1, Pan 1, Pan 2, and CR 5) gave a mean DNA value of 0.34, whereas the nuclei of Plasmodia which develop from each of the four intraisolate crosses had a mean value of 0.63. These values correspond to the 2C haploid level in myxamoebae and the 4C diploid level in Plasmodia. DNA values in two additional isolates (Pan 3 and CR 2) are much higher than the mean for the other five. Accordingly, it is proposed that these may be polyploid. The question of polyploidy inD. iridisand in other myxomycetes is evaluated. The seventh isolate, Ky 1, is taxonomically very close toD. nigripesand was not included in calculations of mean values forD. iridis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11834.x

出版商:Wiley    

年代:1976

数据来源: WILEY