摘要:

Early basidiospore development inCoprinus cinereushas been divided into four stages: 1) inception, 2) asymmetric growth, 3) equal enlargement, 4) elongation, all based on changes in spore size and shape, wall layering, and cytoplasm. The hilar appendix body formed on the adaxial side of the stage 1 basidiospore, persisted through all stages studied, and predicted the site of the hilar appendix. The hilar appendix formed in stage 2 by modification of certain wall layers. A band of peripheral endoplasmic reticulum covered an average of 38 % of the lower spore wall in stage 3 and was oriented around the axis of growth. Stage 4 was initiated by a break in wall layer 3 at the spore apex and the disappearance of the peripheral endoplasmic reticulum. A pore cap formed on the spore apex during spore elongation. The spore wall consisted at first of three layers and became six layered by deposition of layers between two of the initial layers. Cytoplasmic changes associated with spore growth included presence of small vesicles at stage 1 and larger Golgi vesicles later, absence of mitochondria and probable Golgi cisternae from the spore until stage 3, and presence of a zone nearly free of ribosomes and organelles under the spore apex in stage 4. Functions of the hilar appendix body, peripheral endoplasmic reticulum and the different wall layers in control of spore shape are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07599.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

Five New Jersey populations ofAmphicarpum purshii(an annual panicoid grass) were investigated as to total allocation of biomass to reproduction and its distribution between aerial chasmogamous and subterranean cleistogamous inflorescences. Germination of both types of seed was documented, for the first time, in not only the field but under three laboratory temperature regimes. Overall, approximately 29 % of the shoot biomass was allocated to reproduction. On a population basis, subterranean inflorescences accounted for 37–100%of the reproductive biomass, and these seed (5 × heavier but fewer in number) were the source of most surviving seedlings. Subterranean spikelets contained caryopses significantly more frequently than aerial spikelets. The ratio of the number of viable aerial seed to the number of viable subterranean seed increased from 0/4 to 4/2 with recentness and/or frequency of disturbance. As a pioneer species in secondary succession,Amphicarpum purshiiproduces a larger subterranean propagule, with greater seedling vigor and a higher probability of local reproductive success, and also a smaller aerial propagule in larger numbers with potentially greater genetic variability.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07600.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

The distribution of meristematic activity and cell length in the growing internodes of seven species of dicotyledonous vines and three species of monocotyledonous vines is described. InSchlegelia, Ipomoea, Mucuna, Passiflora, Ficus, Thunbergia alata, Dioscorea, Smilax, andVanillathe loss of meristematic activity proceeded from the base to the top of the internode. The absence of isolated meristematic regions is typical of the uninterrupted meristem. InThunbergia grandifloraa small peak of residual meristematic activity is located at the base of the internode, which is typical of the intercalary meristem. The same region of the internode is swollen and functions as a pulvinus. The young internodes of the seven dicotyledonous vines and an additional eight species of monocotyledonous vines with uninterrupted meristems were marked into three segments for growth studies. The upper part of the internode grew more rapidly and for a longer time than the basal part of the internode, except inT. grandiflora. The relative amounts of unequal growth in various species differed widely. Greater growth of the upper region was not correlated with comparable increases in final cell length in the upper region. It is concluded that the uninterrupted meristem is a common feature of shoot extension in many monocotyledons and dicotyledons.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07601.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

Gibberellic acid (GA) treatment of vegetative shoots ofXanthiumleads to a change in phyllotaxis as diagnosed in transverse sections of apical buds. A method of analysis is proposed for estimating the phyllotactic parameters, the plastochron ratio,a, and the divergence angle, α, from measurements of the angular and radial positions of leaf primordia in sections. GA treatment significantly decreases the plastochron ratio,a, from 1.35 in controls, to 1.19 in GA‐treated plants, as shown by an analysis of variance, but has no significant effect on the divergence angle. The estimates ofaand α are compared with the parameters of theoretical phyllotaxis models, leading to the designation (2, 3) for controls, and (3, 5) for GA‐treated plants, where the integers 2, 3, and 5 designate sets of contact parastichies. The change inais interpreted as indicating a change in the relative position at which leaf primordia are initiated in the apical meristem, and this effect is discussed in relation to theories of leaf initiation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07602.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

Plants ofLemna minorL. were grown in axenic culture in order to investigate the direct effect of abscisic acid (ABA) on individual fronds and roots. Both frond and root growth rates were inhibited by 60%, and total growth of both organs was reduced by 30% with ABA concentrations of 2 mg/l. Abscisic acid inhibited frond reproduction, and treated fronds tended to remain attached to parents. Reduction of root elongation and frond expansion occurred within 1–4 hr. Prolonged exposure to ABA inhibited both cell enlargement and cell division in the roots. The results are discussed in the light of current views on the control of growth with endogenous levels of promoter and inhibitor hormones.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07603.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

Endosperm cell and starch granule (amyloplast) development of six maize (Zea maysL.) genotypes,normal, amylose‐extender (ae), sugary (su), waxy (wx), amylose‐extender sugary (ae su), andamylose‐extender waxy (ae wx), was compared. Endosperms of all genotypes were indistinguishable at 14 days after pollination. Cells were highly vacuolated and those in the central crown area of the kernel contained small starch granules in close association with the nucleus. Cellular and nuclear enlargement occurred during endosperm development in all genotypes, and major and minor gradients in physiological age of endosperm cells were observed in all kernels. Amyloplast development varied with genotype. Plastid development innormalandwxcells was characterized by an initial starch granule formation followed by granule enlargement to cell maturity. Endosperms homozygous forae (ae, ae su, andae wx)developed abnormal plastid‐granules. Secondary granule formations preceded development of abnormality inaeandae su, but not inae wxendosperms. In contrast toaeandae sustarch granules,ae wxgranules were highly birefringent indicating a high degree of crystallinity. In all threeaegenotypes, abnormality increased as a function of kernel and physiological cell age. Thesumutant had two distinct effects on amyloplast development. First, a mobilization of the initially formed starch, and second a synthesis and accumulation of phytoglycogen and the formation of large rounded plastids. Inae suplastid development, there was a mobilization of the starch initially formed (resulting in irregularly shaped, nonbirefringent granules) but only small amounts of phytoglycogen were produced.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07604.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

The multilayered structure (MLS) in a spermatid ofMarchantiais the morphogenetic blueprint of the headpiece in a mature sperm. As the nucleus begins elongation, a curved, tapered nuclear projection follows the path of microtubules extending from the MLS and becomes inserted into an indented zone at the rear of the asymmetric organelle. The indented zone defines the most forward penetration of the nucleus into the sperm headpiece. Partial disorganization of MLS lower strata nearest the nuclear projection facilitates overlapping of the nucleus with the rearward part of the anterior mitochondrion. At the front of the nascent headpiece, the mitochondrion is stabilized against microtubules following total disorganization of intervening MLS strata. Penetration of the nuclear projection along the MLS and directed disorganization of MLS lower strata control ultimate disposition of headpiece components. The headpiece is isolated and molded into final shape by undercutting and constriction of the cell membrane.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07605.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

The topologic arrangement of petiolar bundles varies within the length of the cottonwood petiole. Each petiolar bundle is formed by the subdivision and aggregation of acropetally differentiating subsidiary bundles in a predictable pattern. The subsidiary bundles provide vascular continuity between the stem and specific portions of the leaf lamina. Spot‐labeling of individual veins with14CO2, freeze substitution, and microautoradiography were used to establish the relation between the secondary veins of the lamina and the vasculature of the petiole. Within the petiole vasculature each subsidiary bundle was continuous with a specific portion of the lamina and seemed to have a separate function. Subsidiary bundles continuous with the central leaf trace were closely related functionally to the tip region of the lamina, while the subsidiary bundles continuous with the lateral leaf traces were functionally related to the middle and basal portions of the lamina.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07606.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

A new genus,Henricksonia, containing the single speciesH. mexicana, has been described from a locality in north‐central Mexico. It is unique among the genera of the subtribe Coreopsidinae in possessing a pappus of well‐developed scales such as frequently occurs in other subtribes of the Heliantheae. The discovery of four, previously uncollected, monotypic genera among several tribes of the Asteraceae from this region over the past several years suggests that the area is a primary center of diversification for this large family.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07607.x

出版商:Wiley    

年代:1977

数据来源: WILEY

摘要:

An antheridium ofAtrichumcontracts when it opens. This contraction rapidly ejects much of the mass of sperms because a fluid present in the base of the antheridial chamber acts as an hydraulic ram. The residue of sperms is slowly extruded as the same fluid takes up water. Photographs allow the construction of time courses that directly demonstrate the existence of two phases (rapid vs. slow) in sperm release. Antheridia open as quickly in 1msucrose as they do in water. Molar sucrose allows only the rapid phase of sperm release, caused by the contraction of the jacket, and the antheridia remain only partly emptied. This behavior in sucrose solution provides a convenient test for similarities among antheridia. The mechanism of sperm release that occurs inAtrichumoccurs inPolytrichumandMniumas well.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1977.tb07608.x

出版商:Wiley    

年代:1977

数据来源: WILEY