摘要:

Erythroxylum undulatumis a gametophytic apomict that produces about 15% seed set independently of pollination. Embryo sac formation is aposporous, and the plants are largely pollen‐sterile, which may be a result of polyploidy and hybrid origin. It appears to be derived from a distylous ancestor, as all other known species ofErythroxylumare distylous or secondarily dioecious, and all examined individuals ofE. undulatumcorrespond to the normal long–styled morph. This is the first clearly documented case of agamospermy derived from distyly.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12583.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

Carrot cells (Daucus carotaL.) in suspension culture exposed to medium containing 150 mM NaCl plasmolyzed immediately and deplasmolyzed within 35 to 40 hr. Three days after exposure to NaCl the cells resumed proliferation. Accommodation to salinity and renewal of growth was accompanied by absorption of Na+from the external medium. On completion of deplasmolysis, K+concentration in the cytosol doubled and Na+concentration approximated that of K+. The vacuolar K+concentration was practically unchanged while Na+accumulated to a concentration double that of K+. Cl−‐accumulation started later and eventually exceeded that of Na+plus K+. Malate was redistributed during accommodation to salinity and eventually returned to its initial level. Amino acid content in the cytosol increased fivefold, while in the vacuole it remained unchanged. These results show that: 1) recovery from osmotic shock requires absorption of easily penetrating solute, mainly Na+; 2) distribution of solutes, absorbed or synthesized in cells exposed to salinity, is a dynamic process; 3) cells could grow and proliferate in high NaCl content in the cytosol; 4) red beet root cells grown in the presence of NaCl contain higher cytoplasmic Na+than K+; and 5) during adjustment to salinity small spherical carrot cells survive the osmotic shock and do not show any detectable damage.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12584.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

The floral fragrance glands (osmophores) of 18 species ofStanhopeaandSievekingiawere examined through a series of developmental studies at light and electron microscope levels including late bud stages through postanthesis. Various characters were identified to be of potential systematic value and were recorded for each species. These characters included: texture of the osmophore surface, number of distinct cell layers comprising the osmophore, nature of lipid inclusions in osmophore cells, and presence or absence of plastoglobuli in osmophore amyloplasts. These characters were combined with traditional features of floral lip morphology for cladistic analysis.Sievekingiawas the postulated outgroup.Stanhopea ecornutashowed the largest number of plesiomorphic characters.Stanhopea pulla, S. annulata,andS. Candidawere only slightly more derived.Stanhopea anfracta, S. gibbosa, S. martiana, S. oculata, S. radiosa, S. ruckeri, S. saccata, S. shuttleworthii, S. tigrina, S. vasquezii,andS. wardiiform a monophyletic group that can be recognized by a labellum with an articulated epichile and a bicornuate mesochile (or hypochile).Stanhopea tricornismay be a hybrid between a species ofSievekingiaandStanhopea.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12585.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

Polypodium virginianumL. has been treated as a morphologically and chromosomally variable species. Recently, however, two species have been named from within theP. virginianumcomplex. Chromosome counts reported here confirmed that these segregate species,P. appalachianumHaufler and Windham andP. sibiricumSiplivinskij, are diploids withn =37. It was further hypothesized that hybridization between these diploids initiated the allotetraploidP. virginianum.Naturally occurring, sterile triploid plants obtained from habitats in which the putative allotetraploid was sympatric with its presumed diploid progenitors have been verified isozymically as backcross hybrids. Meiotic chromosomal behavior showed that the triploids contained univalents and bivalents in nearly equal numbers, confirming that tetraploidP. virginianumcontained one genome from each diploid. Observation of three to six trivalents in triploid preparations suggested that the diploids are still closely related genetically. This hypothesis was supported by isozymic studies which found a genetic identity of 0.610 betweenP. appalachianumandP. sibiricum,a value much higher than the average identity for congeneric fern species studied to date (0.33) and higher than any other species pair in theP. vulgareL. complex (average I = 0.307). These chromosomal and isozymic data help to resolve a biosystematic riddle that has interested pteridologists for over 40 years.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12586.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

Arachis glanduliferaStalker is a diploid (2n = 2x =20) taxon in sectionArachisnative to eastern Bolivia. Plants ofA. glanduliferahave longer lateral branches than other taxa of sectionArachis,an upright mainstem, prostrate lateral branches, and larger flowers and seeds than other wild species in the section. The pods are greatly reticulated. Glandular trichomes are present on vegetative plant parts and the peg. Intraspecific hybrids among four accessions are fertile and uniformly have ten bivalents in pollen mother cells. Three accessions had nearly identical karyotypes, while a fourth had subtelocentric chromosomes 6 and 9. Hybrids betweenA. glanduliferaand two other diploid species of sectionArachiswere male‐sterile, and chiasmata frequencies ranged between 5.8 and 12.1 per cell. Attempts to hybridize the species withA. hypogaeafailed. A new species description and D genomic classification are proposed forA. glandulifera,which is different from previously described A and B genomes of sectionArachis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12587.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

Levels of outcrossing, using aPgmpolymorphism, were estimated for individuals from ruderal and agrestal populations of the predominantly monomorphic weedSolanum ptycanthum,at the northern edge of its range, and compared to agrestal populations sampled from the southern portion of its distribution. Individuals were grown in agricultural habitats in Ontario. Outcrossing estimates of the northern agrestals were very low (<3%) and did not differ from ruderal estimates. Southern agrestals exhibited much higher outcrossing rates (10%–17%). Of the floral traits measured, degree of stigma exsertion and style position showed interpopulation variation and correlated with outcrossing rate. Outcrossing in northern individuals was largely precluded by the complete overlap in female and male functions and stigmatic surfaces that were in direct contact with anther sacs as the flower opened. The observed flexibility in mating system may have played an important role in colonization success of 5.ptycanthum.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12588.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

The mechanisms by which Venus's Flytrap (Dionaea muscipulaEllis) close are not clearly understood, and several conflicting models have been proposed. We have measured the dynamics of five trap tissues from three trap regions during full closure of young, fully developed, previously unclosed traps. Closure was divided into three distinct stages: 1) Capture–occurred immediately after stimulation of the trigger hairs and involved the rapid inward flexure of the trap margin and tynes. This motion interlocked the tynes, effectively capturing the prey. This was the only rapid movement of the trap; 2) Appression–completed by 30 min poststimulation, was characterized by contact of the margins; and 3) Sealing–completed by 1 hr poststimulation, was characterized by a sealed “digestive” sac formed around the potential prey, also by tight appression and recurved bending of the trap–margins. Major tissue dynamics that facilitated changes in trap morphology (hence, closure) occurred in different regions of the trap during different periods of time. The first regions where activity occurred were the A and C regions (Fig. 1), after approximately 15 min poststimulation; tissues in the C regions were most active followed by those in the B region of the trap (30 min to 1 hr poststimulation). Thus, shape changes during each stage of closure were the result of temporally separated changes in trap tissue volume. The complete sequence of events was elicited by a single 5–sec period of trigger hair stimulation. Our study showed that changes in the curvature of the trap during closure involved the expansion of opposing tissue groups (i.e., on opposite sides of trap medullary tissues). The pressure from contact of opposing trap lobes during the Appression stage may play an important role in regulating further trap closure and morphology.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12589.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

Paraphyllanthoxylon abbottiin. sp. and cf.Plataninium haydeniiFelix from the Paleocene Black Peaks Formation, Big Bend National Park, Texas, are the first Paleocene dicotyledonous woods described from North America. Both represent wood types common in the Cretaceous. There are 30 logs ofParaphyllanthoxylon abbottii;it is rare that a single locality has such as large number of petrified dicotyledonous logs with a similar structural pattern, and the variability in mature wood structure can be documented.Paraphyllanthoxylon abbottiihas a combination of features that occurs in many dicotyledonous families, but it is most similar to genera of Burseraceae. The Big BendParaphyllanthoxylontrees lack distinct growth rings, which suggests they grew in a climate without marked seasonality; they have high (10–74) vulnerability indices; such high values occur in extant tropical trees. The type species ofParaphyllanthoxylon, P. arizonenseBailey was reexamined, and its quantitative features are described.AplectotremasSerlin of Albian age from the Edwards Limestone has anatomy likeParaphyllanthoxylon,and most probably is wood from a tree. The wood designated cf.Plataninium haydeniiFelix resembles extant Platanaceae but differs in having exclusively scalariform perforation plates. Comparison of this wood with other platanoid woods suggests that in platanoid woods there has been a shortening of vessel elements and a decrease in the frequency of scalariform perforation plates from the Cretaceous through the Tertiary. These changes are consistent with the Baileyan model for specialization in tracheary elements.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12590.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

The involvement of the stamens as transporters of plant growth regulators in flowers was examined by measuring the movement of14C‐indole‐3‐acetic acid (IAA) andl4C‐l‐aminocyclopropane‐1‐carboxylic acid (ACC) through floral organs ofIpomoea nil.During the transport of14C‐IAA through isolated filament segments, the polar accumulation of14C‐IAA in receiver blocks increased with time during filament development, which correlated with polar efflux rates at older stages of filament development. An inhibitor of polar IAA transport, 2,3,5‐triiodobenzoic acid, disrupted the polarity of auxin transport by reducing the movement of14C‐ IAA from filaments into receiver blocks. Transport of both14C‐IAA andl4C‐ACC through filaments into other floral organs also was monitored in isolated flower buds in the laboratory and intact buds in the greenhouse. In isolated and intact buds 21 hr before anthesis, substantially higher levels of isotope were recovered in corolla tissue when14C‐ACC was transported through the filaments than when14C‐IAA was transported from the filaments. In isolated buds, substantial levels of both isotopes accumulated in the pistil (69 hr and 45 hr before anthesis), but minimal amounts were observed in receptacle and calyx tissues (69 hr to 21 hr before anthesis). In intact buds, high levels of both isotopes were recovered in receptacle, calyx, and pistil tissues (69 hr to 21 hr before anthesis). The results from this study support the hypothesis thatIpomoeastamens are transporters for ACC and IAA to regulate ethylene production in the corolla and other floral tissues.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12591.x

出版商:Wiley    

年代:1991

数据来源: WILEY

摘要:

This study addressed the hypothesis that phylogenetic changes in plant size at reproductive maturity may have facilitated adaptive radiation ofGeonomaspecies within rain forest understory habitats. Leaf size, leaf form, plant size, and growth form were compared within and among 23 species ofGeonomafrom lowland and montane rain forest areas of Costa Rica and Colombia. Leaf size was significantly correlated with crown height in 18 of the 21 species examined, and with stem diameter in 17 of the species. In species characterized by a gradual ontogenetic transition from bifid to dissected leaves, shoots with bifid leaves were significantly smaller than shoots with dissected leaves with respect to rachis length, number of plications, and stem diameter. Among species, stem diameter below the crown explained 74% of the variation in leaf size (rachis length). Crown height and stem diameter were positively correlated among clustered species, but not among solitary species or all species combined. Leaf dissection was correlated with crown height among the 17 species with dissected leaves; species with bifid leaves were significantly smaller than species with dissected leaves with respect to leaf size and stem diameter. Solitary species had larger leaves and larger stem diameters than clustered species at the same crown heights. Morphological patterns among species generally followed within‐species trends. These patterns suggest thatGeonomaspecies are variants on a generic theme:within and among species, leaf size and complexity of form increase with stem diameter and crown height. Solitary and clustered growth forms appear to be morphologically convergent; within each of these architectural groups, the generic theme still applies. Evolutionary changes in leaf size, leaf form, and plant size, however, have clearly involved other factors in addition to variation in plant size.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1991.tb12592.x

出版商:Wiley    

年代:1991

数据来源: WILEY