摘要:

The chasmogamous/cleistogamous (CH/CL) breeding system has evolved independently many times, but its ecological role has been studied in few species. InTriodanis perfoliata, we studied the natural phenology of flowering and seed set, how successful CH flowers were at setting seed, whether seed from CH and CL flowers differed in germination behavior, and whether plants derived from these two seed types differed in vigor. Most notably, we found that the later the CH flowers were produced, the fewer seed they successfully matured. In general the two seed types did not show differences in germination behavior, but for some maternal parents the two seed types differed. For these, the CL seed germinated less readily. Finally, there was some indication that plants from CL seed were not as vigorous as those from CH seed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13521.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Fossil fruits and a vegetative axis assignable to the extant genusCeratophyllumare described from four North American Tertiary localities. Fossil fruits assignable to the extant speciesC. muricatumandC. echinatumare reported from the Eocene Green River and Claiborne formations, and the Miocene Esmerelda Formation, respectively. An extinct species,C. furcatispinum, is described from the Paleocene Fort Union Formation and represents the oldest published report ofCeratophyllumin the fossil record. The existence of extant angiosperm species in the Eocene is very unusual and may be attributable in this case to slow evolutionary rates and unusual evolutionary properties associated with hydrophily in the genusCeratophyllum.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13522.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Rhodamine‐phalloidin was used to determine the distribution of actin microfilament bundles (mfb) in cells thought to be the site of gravity perception (statocytes) in coleoptiles and root caps ofZea maysandHordeum vulgare.In coleoptile cells, amyloplasts were usually observed in close proximity to thick mfb, which often appeared to divide into finer mfb adjacent to individual amyloplasts. The nucleus in these cells was surrounded by an extensive network of mfb, which were connected to thicker transvacuolar mfb. Columella cells of the root cap contained an extensive reticulum of fine mfb throughout the protoplast, but lacked the much thicker mfb seen in coleoptile cells. The distribution and extent of mfb observed in fixed cells correlates with patterns of streaming and amyloplast movement seen in living cells. A possible role for actin mfb in the perception of gravity is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13523.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Pollen morphology of 15 species ofSiphonoglossaand of two closely related groups was investigated. Two tribal‐specific pollen types are found withinSiphonoglossasensu lato suggesting that the genus is artificial, composed of taxa belonging in several genera among two tribes (subtribes sensu Bremekamp) of Acanthaceae. Five taxa currently included in an informal subgeneric category ofSiphonoglossahave tricolporate, prolate pollen (termed Type I) that is characteristic of Odontonemeae (= Odontoneminae, Justicieae). Pollen of the remaining taxa, belonging in two formal sections of the genus, are mostly 2‐porate, bilateral (Type II) with a sexine sculpturing characteristic of Justicieae (= Justiciinae). Pollen of sectionSiphonoglossais rather uniform, 2‐porate, bilateral with lolongate pores, and seem to delimit a natural group. Taxa of sectionPentalobahave a more heterogeneous pollen morphology, mostly 2‐porate, bilateral with lalongate pores. Controversial aspects of the interpretation of pollen morphology in Justiciinae are presented and their relevance to this study are examined. Hypothetical trends in the evolution of pollen of Justiciinae are discussed and the application of pollen morphology to taxonomy of the genus is presented, including a recommendation for narrowing the generic concept ofSiphonoglossato the taxa of the type section.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13524.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Filament growth in the morning gloryIpomoea nilis promoted by gibberellic acid (GA3) and inhibited by ethylene production during the earlier stages in development (Koning and Raab, 1987). The effects of anther removal on filament growth were examined inI. nil.Three‐quarters of the calyx and corolla tissues were removed in order to emasculate the stamens. This removal caused filament growth to be inhibited in the intact stamens (69 hr before anthesis) as well as the emasculated stamens (69 to 21 hr before anthesis). When the ethylene biosynthesis inhibitors CoCl2and aminoethoxyvinylglycine (AVG) were applied in separate experiments (to eliminate wound ethylene generated by the damaged tissues), filament growth was promoted to control levels observed in intact flower buds (69 hr before anthesis). Our data suggest that the wounding effect from the calyx and corolla tissues and subsequent reduction in filament growth override any observable effects with anther removal on filament growth. Apparently, the removal of the calyx and corolla tissues severs a normal hormonal relationship between these floral organs and the developing filament.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13525.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Leaf development in the normal (lobed margin) and the solanifolia (sf/sf) mutant (entire margin) of tomato (Lycopersicon esculentum) was compared at the light and scanning electron microscope levels. The shoot apices of the mutant plants contained microbodies near the axil of the youngest leaf, which were absent in the normal plants. The structural and morphological events in the initiation of leaf primordia were similar in the two genotypes. The pattern of leaflet emergence was also similar in the two types of plants, but the timing of leaflet production was different. The first pair of leaflet primordia in the normal plants was produced on P3, whereas in the mutant it was not produced until P5. The adult leaves of sf/sf plants were larger than those of normal, and the greater leaf area in the mutant was associated with a greater adaxial epidermal cell and areole area. A continuous marginal fimbriate vein (MFV) was present along the margin of each of the normal leaflets. However, a continuous MFV was absent in the mutant leaflets. It is suggested that the absence of a continuous MFV in the mutant might alter the nutritional and hormonal supply to the leaf margin, which ultimately leads to a modified leaf, i.e., with an entire margin.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13526.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Enzyme electrophoresis was employed to ascertain the number of loci encoding plastid phosphoglucose isomerase (PGI) in species representing all sections of North AmericanCoreopsis.Several species from each of the closely related generaBidens, Coreocarpus, Cosmos, andThelespermawere also examined. Species in nine of the 11 sections of North AmericanCoreopsishave two isozymes for plastid PGI, and nearly all species examined in the four other genera also have two (one species has three) isozymes. Since most diploid vascular plants have one plastid PGI isozyme, a gene duplication probably occurred in an ancestor that is common toCoreopsisand the other four genera. That is, two isozymes represent the ancestral number forCoreopsis.The two sections (ElectraandAnathysana) apparently lacking the duplication are closely related woody plants restricted largely to Mexico. One gene encoding plastid PGI ostensibly was silenced in a common ancestor of these two sections. This is concordant with other data suggesting a close relationship between the two sections, i.e., they appear to represent a monophyletic group. The electrophoretic data also indicate that 1) the enigmatic monotypic sectionSilphidiumis more closely related to eastern North American sections and not derived from sectionElectra; and 2) sectionAnathysanais not ancestral to the three California sectionsLeptosyne, Pugiopappus, andTuckermannia; rather, it represents a terminal element closely related to and possibly derived from sectionElectra.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13527.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Vesicular‐arbuscular mycorrhizae (VAM) are reported for the first time in four species of Hawaiian Ericales,Vaccinium calycinum, V. dentatum, andV. reticulatumof the Ericaceae andStyphelia tameiameiaeof the Epacridaceae. The coarse roots (>1.5 mm diam) of many specimens were densely colonized by VAM fungi, with up to 90% of the length of roots containing arbuscules, vesicles, coils, and internal hyphae. Spores of an undescribedGlomussp. were associated with two species ofVaccinium.The hair roots of all species bore the ericoid mycorrhizae typical of certain families of this order. The high frequency of VAM in Hawaiian populations of Ericales suggests that ancestral Ericales possessed the capacity to form both VA and ericoid mycorrhizae. An evolutionary sequence of mycorrhizal dependency in the Ericales is presented.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13528.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Briza maxima(quaking grass) is a cosmopolitan grass common to Europe and North and South America. It grows in disturbed soils and on roadsides. The hemispherical caryopsis is embedded between a leaflike lemma and flattened palea. The embryo is of the festucoid type. The scutellum shows two surrounding ridges at the edge of the scutellum/endosperm boundary, and has lateral lobes. A broad epiblast extends toward the embryo apex and is continuous with the dorsal surface of the coleorhiza. The single‐layered aleurone surrounds the starchy endosperm and is discontinuous around the embryo. The caryopsis coat is thin, except at the placental pad where it is thickened by the pigment strand and the nucellar projection.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13529.x

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

A comparative developmental study of the inflorescence and flower ofHamamelisL. (4‐merous) andLoropetalum(R. Br.) Oliv. (4–5 merous) was conducted to determine how development differs in these genera and between these genera and others of the family. Emphasis was placed on determining the types of floral appendages from which the similarly positioned nectaries ofHamamelisand sterile phyllomes ofLoropetalumhave evolved. InHamamelis virginianaL. andH. mollisOliv. initiation of whorls of floral appendages occurred centripetally. Nectary primordia arose adaxial to the petals soon after the initiation of stamen primordia and before initiation of carpel primordia. InLoropetalum chinense(R. Br.) Oliv. floral appendages did not arise centripetally. Petals and stamens first arose on the adaxial portion, and then on the abaxial portion of the floral apex. The sterile floral appendages (sterile phyllomes of uncertain homology) were initiated adaxial to the petals after all other whorls of floral appendages had become well developed. In all three species, two crescent shaped carpel primordia arose opposite each other and became closely appressed at their margins. Postgenital fusion followed and a falsely bilocular, bicarpellate ovary was formed. Ovule position and development are described. The nectaries ofHamamelisand sterile phyllomes ofLoropetalumrarely develop as staminodia, suggesting a staminodial origin. However, these whorls arise at markedly different times and are therefore probably not derived from the same whorl of organs in a common progenitor. This hypothesis seems probable when one considers that the seemingly least specialized genus of the tribe,Maingaya, bears whorls of both staminodia and sterile phyllomes inside its whorl of stamens.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1990.tb13530.x

出版商:Wiley    

年代:1990

数据来源: WILEY