Cytogenetic studies of cultivatedCrocus sativus (Iridaceae)

Meiosis and mitosis are described in cultivatedCrocus sativus of Iran. This indicates that this species is an autotriploid and sterile. Karyotype analysis, rare inversions, laggard chromosomes and distribution of chromosomes in the first anaphase are described, and the reasons for its sterility are given.     

Flow cytometric analysis of nuclear DNA inCrocus sativus and allies (Iridaceae)

The genome size and base composition of the triploidCrocus sativus and its two diploid most probable ancestors,C. cartwrightianus andC. thomasii, was investigated and compared inter- and intra-specifically by means of flow cytometry. There was little variation inC. sativus and little difference fromC. cartwrightianus. Crocus thomasii was significantly different from the others.Crocus cartwrightianus is the most probable diploid ancestor ofC. sativus.     

Self-incompatibility inCrocus vernus subsp.vernus (Iridaceae)

Outcross, self- and mixed pollinations were performed inCrocus vernus subsp.vernus, a species with bicellular pollen, dry stigmas and hollow style. No differences were noted among the above pollinations concerning the germination of pollen and the growth of pollen tubes until the top of ovary. Within 45 min after pollinations 62% of pollen grains germinated. Pollen tubes penetrated the papilla cuticle extending along the papilla wall; on entry into stigmatic lobes they continued growth in the stylar secretion to ovarian locules. Here, however, self-pollen tubes failed to reach or to enter the ovule micropyle; while pollen tubes from either outcross- or mixed pollinations grew until fertilizing ovules. These observations gave evidence of a self-incompatibility system inCrocus, which appeared to be neutralized by mentor effect. The ovary as site of incompatibility response is discussed.     

Chromosome counts inPosidonia (Posidoniaceae)

The five species ofPosidonia occuring in Western Australia all have a diploid chromosome number of 20.     

Chromosome counts inCephalotus (Cephalotaceae)

Cephalotus follicularis is uniformly n = 10 in all populations surveyed.     

Intra- and interspecific reproductive barriers inCrocus (Iridaceae)

The reproductive system was studied inCrocus genus (Iridaceae) following intra- and interspecific pollination, by using light and scanning electron microscopy. The results suggest that the stigma-style tract of theCrocus pistil is a mere promoter of pollen tube growth, while intra- and interspecific discrimination of compatible and incompatible pollen occurs in the ovarian tract. Here, the transmitting tissue consists of special epidermal cells, whose granular or floccular secretions provide the selective medium for the growth of pollen tubes. The ovarian self-incompatibility (SI) is widespread within the genus, resulting in a partial or complete suppression of self-fertilization. Moreover, postzygotic SI mechanisms, as well as postzygotic mechanisms of unknown nature, seem to be recurrent and both are responsible for seed abortion. The interspecific ovarian incompatibility concerns only unrelated crosses; crosses between related fertile species succeed both in fertilization and seed-set.     

Chromosome counts inCalea (Asteraceae-Heliantheae)

Chromosome numbers are reported for six taxa ofCalea, among them tetraploidC. septuplinervia, the only known polyploid inCalea s. str. The base chromosome number ofCalea is interpreted as x = 19.     

Evolution of herkogamy and gynodioecy in Moroccan species ofRomulea (Iridaceae)

Herkogamy and gynodioecy were studied in the Moroccan species ofRomulea. Several types of herkogamy are shown to occur in the different species, with each type corresponding to a characteristic perianth size. The degree of differentiation between female and hermaphrodite morphs varies among the different gynodioecious species. Herkogamy is considered to have evolved prior to the development of the gynodioecious condition. An evolutionary interpretation is proposed based on the degree of herkogamy and of gynodioecy in the different species.     

Robertsonian change in allies ofZebrina (Commelinaceae)

Meiotic pairing inTradescantia soconuscana 2n=26 (6M+16A+4T) suggests that it has a tetraploid constitution which is not apparent in its chromosome number. Its nombre fondamental of 32 indicates that it could have evolved from an ancestor with x=8 by a combination of Robertsonian fusion, hybridization and polyploidy. The 2n=16 (8A+8T) karyotype of a closely related diploid supports this. The allied genusZebrina may have followed a similar method of chromosome evolution.     

A study on pollen grains ofCrocus cartwrightianus (Iridaceae)

Crocus cartwrightianus andC. cartwrightianus cv.albus pollen have been studied from structural and ultrastructural points of view and the germination assayed in vivo and in vitro.C. cartwrightianus pollen is regularly shaped and sized, has a low percentage of anomalous grains and has a high germination rate in vitro, whileC. cartwrightianus cv.albus is less regularly shaped with some variation in size and has a high percentage of anomalous grains and a low germination percentage in vitro. Ultrastructural observations have revealed, in the pollen of both the taxa, the presence of a thin elongated vegetative nucleus and a generative cell surrounded by a thin membrane. However,C. cartwrightianus pollen shows a thicker intine, andC. cartwrightianus cv.albus shows numerous pollen germination anomalies which are in common withC. sativus.     

Chromosome numbers in AustralianEuphrasia (Scrophulariaceae)

Chromosome numbers for six Australian taxa ofEuphrasia have been determined. Improved staining techniques have shown that numbers for four of the taxa published previously by the first author were incorrect. The investigated taxa show high ploidy levels with an apparent base number of x = 11, the same as for the genus outside Australia.Dedicated to Prof. DrElisabeth Tschermak-Woess on the occasion of her 70th birthday.     

Chromosomal differentiation withinCrocus vernus agg. (Iridaceae) in the Carpathian Mts.

Western and eastern Carpathian populations ofCrocus heuffelianus s. lat. (incl.C. scepusiensis) have 2n = 18 but differ in karyotype. While western populations are chromosomally monomorphic, eastern populations exhibit geographical karyotypic differentiation.     

Phenotypic plasticity and character differentiation in a subdivided population ofIris pumila (Iridaceae)

Variation patterns in phenotypic plasticity and broad sense heritability of 26 characters were examined within and among closely adjacent habitats of the bearded iris,Iris pumila. It was found thatI. pumila has considerable differentiation for phenotypic plasticity and genetic variation over short distances. An analysis of relationships between character differentiation and phenotypic plasticity suggests that they could have evolved independently. Possible mechanisms for maintaining local differentiation of the observed plastic and genetic variation are also discussed.     

Maternal effects on early juvenile traits inIris pumila (Iridaceae)

The variation in the maternal effects on a number of the earlyIris pumila seedling traits expressed under high and low light levels in a growthroom was studied. A reciprocal crossing design was used for the establishment of 20 full-sib families. Each family consisted of two maternal groups differing only in genotype used as a seed parent. Maternal variation was estimated from the variance between maternal groups within sibships. Two parameters for maternal variation were computed: the maternal effects coefficient m² and the coefficient of maternal variation CV_M. Maternal effects significantly accounted for the phenotypic variation in seed mass and most of the early seedling traits. Light conditions prevailing during the seedling development markedly influenced overall structure of maternal correlations. Implications of maternal correlations on the integration of juvenile phenotype have also been discussed.     

Pregamic and postgamic self-incompatibility systems inCrocus (Iridaceae)

Ovule fertilization and seed set were investigated inCrocus thomasii andCrocus vernus subsp.vernus, after different matings. The results gave evidence for a strict ovarian barrier inC. thomasii, which prevents self-fertilization either in self- or mixed- and double-pollination. InC. vernus the ovarian barrier to selfing is not so effective, but a further incompatibility reaction is expressed after self-fertilization resulting in a complete failure of embryogenesis. The implications of the present observations in respect to the mechanisms of pregamic- and postgamic rejection, indicate that a gametophytic system of self-incompatibility controls the ovule fertilization, and a not yet defined system of self-incompatibility controls embryogenesis.     

Chromosome number of theOxalis tuberosa alliance (Oxalidaceae)

Twelve taxa of theOxalis tuberosa alliance were analysed and found to share the same basic chromosome number x = 8. The karyotypes are composed by small metacentric and submetacentric chromosomes. Different ploidy levels were found among the taxa: there were 9 diploids, 1 tetraploid, 1 hexaploid and 1 octoploid. The last ploidy level corresponds toO. tuberosa, the only tuber bearing taxon found so far in the alliance. Cytotaxonomic evidence and evolutionary considerations suggest to classify theO. tuberosa alliance in sect.Herrerea.     

Beetle pollination of peacock moraeas (Iridaceae) in South Africa

The peacock moraeas are South African geophytes withIris-like flowers that are characterized by broad outer tepals with iridescent spots. Three of the seven species were studied and found to be exclusively visited and pollinated by beetles. The primary pollinators were hopliine (Scarabaeidae) beetles in the generaPeritrichia, Monochelus, Anisonyx andAnisochelus. These beetles visit flowers for nectar, pollen and mating.Peritrichia rufotibialis was the primary pollinator ofMoraea villosa, P. abdominalis was the primary pollinator ofM. tulbaghensis, whileMonochelus sp. nov. was the primary pollinator of the third species,M. neopavonia. High levels of fruit set attest to the effectiveness of these beetles as pollinators. Average fruit set ranged from 83.5 ± 34.8% (M. villosa) to 97.2 ± 11.6% (M. tulbaghensis). Average seed set in the various populations was more variable, but was also quite high, ranging from 77.3 ± 40.8 (M. villosa) to 342.2 ± 115.0 (M. neopavonia) seeds per capsule. Although hopliine beetles are abundant and diverse in southern Africa and commonly visit flowers, this is the first well-documented report of pollination by these beetles.     

Biosystematic studies in European species ofGladiolus (Iridaceae)

Representative specimens of the EuropeanGladiolus species (excl.G. palustris) were used to study variability and relationships. 25 characters were measured for cluster, principal component and Wells hybrid analyses (Figs. 1–3). Three (with PCA) respective five (cluster analysis) main groups are revealed. Bulb characteristics appear to be very useful for indentification. The subspecific status ofG. communis subsp.byzantinus is confirmed. Hybrids of four different parental combinations were detected in our collection. Most species include polyploid series. Partly 3x, 4x, 6x, 8x, 12x and aneuploid cytotypes but no diploids were found. Polyploids as pioneers and hybridization of sympatric species are apparently linked to migrations during the glacial periods.     

Seed coat structure ofCrocus vernus agg. (Iridaceae)

Cytotypes of theCrocus vernus aggregate differ slightly in their seed surface patterns.Crocus albiflorus may be grouped together withCrocus vernus subsp.vernus, both are relatively easily distinguishable by their seed surface patterns from theCrocus scepusiensis—Crocus heuffelianus group.     

Geographic variability of flower colour inCrocus scepusiensis (Iridaceae)

The distribution of four variants for flower colour ofCrocus scepusiensis in the northern part of the Western Carpathians is described. The frequency of white stigmata morphs declines from east to west. In the center of the area stigmata colour morphs show strikingly patchy distribution. White perianth morphs usually occur at low frequencies and their distribution with minor exceptions is restricted to the central part of the area, where patchy distribution of the morphs is a rule. These distribution patterns suggest that the founder effect has played a major role in determining the genetic composition of individual populations. The cline for stigmata colour may also be explained by the dynamics of population expansion. No influence of selection can be demonstrated, but the association between perianth and stigmata colour, and the excessively low frequency of white perianth morphs may imply that the polymorphisms are not selectively neutral.