摘要:

The spicate inflorescence ofSaururus cernuusL. (Saururaceae) results from the activity of an inflorescence apical meristem which produces 200–300 primordia in acropetal succession. The inflorescence apex arises by conversion of the terminal vegetative apex. During transition the apical meristem increases greatly in height and width and changes its cellular configuration from one of tunica‐corpus to one of mantle (with two tunica layers) and core. Primordia are initiated by periclinal divisions in the subsurface layer. These are “common” primordia, each of which subsequently divides to produce a floral apex above and a bract primordium below. The bract later elongates so that the flower appears borne on the bract. All common primordia are formed by the time the inflorescence is about 4.4 mm long; the apical meristem ceases activity at this stage. As cessation approaches, cell divisions become rare in the apical meristem, and height and width of the meristem above the primordia diminish, as primordia continue to be initiated on the flanks. Cell differentiation proceeds acropetally into the apical meristem and reaches the summital tunica layers last of all. Solitary bracts are initiated just before apical cessation, but no imperfect or ebracteate flowers are produced inSaururus. The final event of meristem activity is hair formation by individual cells of the tunica at the summit, a feature not previously reported for apical meristems.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06219.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Twelve allozyme loci were examined in a complex of closely related diploid (2n= 18) members of the genusChenopodiumoccurring in the western United States. These plants are generally treated taxonomically as belonging toC. atrovirens, C. desiccatum, C. hians, C. leptophyllum, andC. pratericola. Also included were populations referable toC. incognitum. The enzymes examined and the allelic designations are given as follows: leucine aminopeptidase,Lap;phosphoglucoisomerase,Pgi‐1, Pgi‐2;glutamate‐oxaloacetate transaminase,Got‐1, Got‐2, Got‐3;glutamate dehydrogenase,Gdh;phosphoglucomutase,Pgm‐1, Pgm‐2;malate dehydrogenase,Mdh‐1, Mdh‐2;and malic enzyme,Me. All populations were fixed for the same allele atGdh, Pgi‐2, andMdh‐1. Chenopodium hianswas fixed for a unique allele atGot‐3and contained two alleles at theLaplocus and two atPgi‐1which were not detected elsewhere.Chenopodium leptophyllumlikewise has unique alleles atLapandPgi‐1. The other three taxa,C. atrovirens, C. desiccatumandC. pratericola, have alleles atLapandPgi‐1which were not found inC. hiansorC. leptophyllum. The former three species have the same alleles in highest frequency at all polymorphic loci exceptMe, whereC. desiccatumis consistently separable fromC. atrovirensandC. pratericola. Allozyme data are concordant with information from morphology, flavonoid chemistry and seed protein profiles in suggesting that: (1)Chenopodium hiansandC. leptophyllumare best regarded as distinct species; (2)C. atrovirensandC. pratericolaare very similar and perhaps should not be recognized at the specific level; (3) C.desiccatumappears most closely allied toC. pratericola;(4) plants referable toC. incognitumrepresent two biological entities, one the same asC. atrovirens, and the other conspecific withC. hians;(5) little genetic variation is detectable in any taxon of these weedy annuals; (6) interspecific hybridization is not a cause of taxonomic difficulties in these plants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06220.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

The pollen antigens of variousAmbrosiaand related species were studied to learn whether substances closely related to antigen E (the major allergen ofAmbrosia artemisiifolia)were present. After conventional immunoelectrophoresis, pollen extracts from sixAmbrosiaspecies each produced at least one pronounced precipitin line with antiserum for purified antigen E. Electrophoretic mobility was the same for several species (A. artemisiifolia, A. bidentata, A. psilostachya, andA. trifida)but was relatively lower forA. acanthicarpaandA. ambrosioides. Precipitin rings were also produced when pollen extracts of the variousAmbrosiaspecies were subjected to radial immunodiffusion in agarose which contained antiserum for purified antigen E. There was great variation among theAmbrosiaspecies with respect to precipitin ring diameters. The variation may be due to differences among species in content of the antigen E‐like substances or to altered interaction with the immobilized antibody. Crossed (2‐dimensional) immunoelectrophoresis was shown to be useful for characterizingAmbrosiapollen antigens. Pollen extracts fromA. artemisiifoliaproduced eight pronounced precipitin bands and at least eight faint, relatively fast‐moving bands after crossed immunoelectrophoresis with antiserum against a whole pollen extract from the same species. One of the pronounced bands contained antigen E.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06221.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

A comparative study of microsporogenesis in fertile and in male sterile (ms1) soybean plants (Glycine max(L.) Merr.) was conducted by using various microscopic techniques. Once the developmental pattern for fertile microsporogenesis was established, it was compared with the developmental pattern in sterile plants to determine the time of microsporogenesis breakdown. Sterility of thems1mutant is caused by failure of cytokinesis after telophase II. The four nuclei resulting from meiosis become enclosed in a single‐celled structure, termed a coenocytic microspore. These microspores develop a pollen‐like wall and become engorged with lipid and starch reserves. Coenocytic microspores usually degenerate after engorgement. This study of fertile and sterile (ms1) microsporogenesis has shown that nuclear and cytoplasmic events must occur at precise times for the successful development of 1npollen grains from 2nsporogenous cells. Any disruption during this process leads to sterility.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06222.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Plastids were observed in all stages of laticifer differentiation inPapaver somniferumL. Plastids in laticifer initials were present as proplastids that later developed electron‐dense inclusions, but never possessed the thylakoids or starch grains that characterize chloroplasts in other cells. Electron‐dense inclusions in laticifer plastids were membrane‐bound and appeared to arise from the accumulation of material within an invagination of the inner plastid membrane. Cytochemical studies of these plastid inclusions indicated that their matrix was not composed of crystalline protein, α‐amylose, amylopectin or polysaccharide. The results suggest that the electron‐dense, membrane‐bound inclusions in laticifer plastids may be composed of lipoprotein.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06223.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Membrane‐bound inclusions in laticifer plastids ofPapaver bracteatumLindl. were examined by electron microscopic enzyme cytochemistry. Electron‐opaque reaction products were observed in the plastid inclusions of laticifers in tissues incubated in 3,4 dihydroxyphenylalanine (dopa), tyrosine, or 3,3 diaminobenzidine (DAB). The enzymatic basis for substrate oxidation was confirmed by the absence of reaction product in boiled controls. Oxidation of dopa and tyrosine in plastid inclusions was not inhibited by sodium diethyldithiocarbamate (DDC), although DDC did inhibit the formation of reaction product between chloroplast lamellae in non‐laticiferous cells. Reaction product was also observed in tissues incubated in dopa and subsequently treated with catalase or catalase plus DDC. DAB oxidation was observed at pH 9.0 and 7.3, in tissues preincubated in aminotriazole (AT) and when hydrogen peroxide was omitted from the DAB medium. The results suggest that peroxidases in the inclusions of laticifer plastids may be responsible for substrate oxidation, even though exogenously applied catalase failed to inhibit dopa oxidation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06224.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Vegetative structural features ofIdiospermum, a monotypic ranalean genus rediscovered in 1972, are described and contrasted with comparable features ofCalycanthusandChimonanthus(Calycanthaceae) to note resemblances and differences. The leaf trace pattern and nodal anatomy of Calycanthaceae and Idiospermaceae (one‐trace and unilacunar) are very similar. The nodal anatomy of certain highly reduced leaves (scale leaves) ofIdiospermumis, however, two‐trace and unilacunar. The microscopic wood anatomy ofIdiospermumis distinctively different in a number of respects from that of the Calycanthaceae. Although there are similarities, it is suggested that the floral anatomy and vegetative features ofIdiospermumset it apart sufficiently from the Calycanthaceae to justify family rank as the Idiospermaceae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06225.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Permineralized specimens of the pollen organGothania(Hirmer) consist of a primary axis bearing pollen cones in the axils of bracts that are four ranked. The bilaterally symmetrical primary axis consists of a uniform parenchymatous pith surrounded by up to 15 endarch‐mesarch axile bundles. The cortex is two‐parted and consists of an inner zone of subepidermal fibers. Bract traces arise from the ends of the ellipsoid stele. Traces to the cones are derived from the open ends of the stele, and at higher levels form a centrarch‐medullated vascular system. Each pollen cone is constructed of up to 25 helically arranged scales, each vascularized by a single trace that may dichotomize. Scales are elongate and broad, and histologically composed of mesophyll parenchyma and fibrous layers. Stomata are restricted to the adaxial surface between rows of fibers. Up to 10 distal scales may be fertile, each with 4 elongate pollen sacs at the tip. Large monosaccate grains of theFelixipollenites‐type are densely packed in each pollen sac. The well‐preserved specimens ofGothaniaprovide an opportunity to compare this genus with pollen cones assigned to the genusCordaianthus, and to relate isolated plant organs to the Cordaitales.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06226.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Rhizomes and attached leaves ofPhyllospadix scouleriHook, were collected in the intertidal zone along the central California coast and exposed to a solution of NaH14CO3in seawater under controlled laboratory conditions. Over a 90‐min period roots and rhizomes absorbed very little14C compared to leaves. Translocation during that time was minor. Plants pretreated with the photosynthetic inhibitor DCMU showed no14C uptake, indicating that under normal circumstances the carbon which is absorbed by leaves is fixed and accumulates as photosynthate. The rate of gross photosynthesis was about 13 mg CO2g dry wt−1hr−1. Gross photosynthesis of wet leaves exposed to14CO2in air was significantly less than leaves exposed to NaH14CO3. The effect of a leaf‐grazing limpet (Notoacmea paleacea)on leaf anatomy and14C uptake is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06227.x

出版商:Wiley    

年代:1979

数据来源: WILEY

摘要:

Proline accumulation by eight major species of salt marsh halophytes was examined under growth chamber and field conditions. When the plants were exposed to increasing salinities in the growth chamber, they accumulated proline after a threshold salinity had been reached. Three general patterns were apparent.Limonium carolinianum(Walt.) Britt. andJunius roemerianusScheele began to accumulate proline at 0.25mNaCl with accumulations up to 63.6 μmoles per gram fresh weight at higher salinities. The C4grasses,Spartina alternifloraLoisel.,Spartina patens(Aiton) Muhl., andDistichlis spicata(L.) Greene, had threshold salinity levels around 0.5mNaCl and accumulated proline to 27.4 μmoles per gram fresh weight. The succulents,Salicornia bigeloviiTorr.,Salicornia virginicaL., andBorrichia frutescens(L.) DC, did not accumulate proline until very high salinities (0.7 m) were reached. Water stress imposed by polyethylene glycol instead of NaCl caused similar proline accumulation in the species studied, but to different extents. Field measurements of proline content and soil salinities correlated well with the findings from growth chamber experiments. Rates of proline accumulation and breakdown inL. carolinianumwere sufficient for osmotic adjustment by the plant to the changes in interstitial salinity in the marsh. The significance of proline accumulation as an adaptation to the salt marsh environment was species specific. We suggest that proline accumulation is of considerable importance inL. carolinianumandJ. roemerianus, important to the C4grasses at certain times and in certain locations in the marsh, and of little importance in the succulents.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1979.tb06228.x

出版商:Wiley    

年代:1979

数据来源: WILEY