The chemotaxonomy ofGeranium (Geraniaceae)

Relationships amongGeranium species constituting sectt.Anemonifolia, Lucida (monotypic) andRuberta together with representatives of sect.Unguiculata were investigated by gas-chromatographic study of essential oils, electrophoretic comparison of seed proteins and chromatographic separation of nectar amino acids. — Essential oil study gave little information.G. macrorrhizum (sect.Unguiculata) had far greater quantities of essential oils in its foliage than other species and differed from them qualitatively. — Species of sectt.Anemonifolia andRuberta, together withG. cataractarum (sect.Unguiculata), between them yielded 19 seed protein bands; the distribution of these indicated close relationship among the species and was consistent with hypotheses for the origin of certain species by alloand autopolyploidy partly within the group. Involvement of an unknown species in the origin of two allopolyploids was implied. Separate origins for the two octoploid species in this set are also inferred. In two instances there was evidence for the transformation of one band into another subsequent to the separation of related species. The inference of allopolyploidy was supported by the occurrence of additivity of parental bands shown by an artificial hybrid between two of the species. A model for the evolutionary divergence of the seed protein patterns is presented. Two species outside the above set appeared less closely related; they wereG. lucidum andG. macrorrhizum (sect.Unguiculata) and between them they showed 6 additional bands, four of which were shared. — Of 18 nectar amino acids found, 4 to 15 occurred in any one species, with low numbers (4 and 8) occurring in the most extreme inbreeders. The spectra of nectar amino acids of two hybrids showed additivity of those of the respective parents. The results echo rather closely those provided by seed proteins, but in the absence of data from outside the group their taxonomic significance is uncertain. However, the divergence between the two octoploids was again evident.     

Additional chromosome numbers inPelargonium (Geraniaceae)

Mitotic chromosome counts were made from field collected and subsequently cultivated plants of 61Pelargonium species from 14 sections. The 33 new results are presented. 47 of the species have a basic number of x = 11, nine spp. of x = 9 and five spp. of x = 8. 17 spp. are polyploid. In two sections species with different basic numbers occur, which is of interest for the subgeneric classification. The size of the chromosomes varies between the investigated species. Most but not all species with x = 11 have short, those with x = 8, 9 large, and only exceptionally short chromosomes. Within sections chromosome size is not always uniform. The relationship between the different basic chromosome numbers is discussed.     

Systematic revision ofErodium (Geraniaceae) in Egypt

A key is provided for the 14Erodium species of the Egyptian flora. The important differential chracters of leaf, inflorescence, flower, and fruit are discussed and illustrated.Systematic Revision ofGeraniaceae in Egypt, I.     

Fertility relationships ofGeranium (Geraniaceae): sectt.Ruberta,Anemonifolia, Lucida andUnguiculata

Cross-pollinations were carried out among 11 briefly described species ofGeranium. Eight species pairs produced hybrids, of which five had not been reported before. The close relationship ofG. purpureum, G. robertianum andG. rubescens (sect.Ruberta) was confirmed; they form a polyploid series (diploid, tetraploid and octoploid on base x = 16). ForG. canariense (sect.Anemonifolia), another octoploid on base x = 16, the results suggest greater affinity with the former section.G. maderense andG. palmatum of sect.Anemonifolia (2n = 68) are confirmed as closely related to each other.G. maderense produced hybrids withG. robertianum (2n = 64; sect.Ruberta) and withG. cataractarum (2n = 36; sect.Unguiculata). Meiosis in the latter hybrid suggests allopolyploidy between parents with 2n = 32 and 2n = 36. Whereas all these species clearly form a very close alliance,G. lucidum (sect.Lucida) andG. macrorrhizum andG. dalmaticum (both sect.Unguiculata), appear genetically more isolated from them. One plant ofG. macrorrhizum ×G. dalmaticum was raised. — In crosses where hybrids or non-germinating seeds resulted, the reciprocal cross in the majority of cases produced a greatly inferior result or none at all. This asymmetry of response could in some cases be explained by inability of pollentubes from short-styled parents to reach the ovary of a long-styled species and in others by a modification of Hogenboom's theory of incongruity, but neither explanation works for every case. In all our asymmetric results where the ploidy level differed the diploid was the successful female, not the tetraploid, as is usually the case. — Some variation in results from year to year could be attributed to weather conditions.Dedicated to Hofrat Univ.-Prof. DrK. H. Rechinger on the occasion of his 80th birthday.     

Delimitation ofPelargonium sect.Glaucophyllum (Geraniaceae)

Pelargonium otaviense Knuth andP. spinosum Willd. are excluded from sect.Glaucophyllum, whileP. grandiflorum (Andr.)Willd.,P. patulum Jacq. andP. tabulare (Burm. f.)L'Hérit. of sect.Eumorpha are included. Sect.Glaucophyllum is characterized by green to glaucous vegetative organs and zygomorphic white to pink corolla with five narrow petals. All the species have an identical pollen and chromosome morphology, the same basic chromosome number (x = 11) and similar flavonoid patterns. A close relationship between sect.Glaucophyllum and sect.Pelargonium is indicated by the occurrence of natural hybrids and concordant characters. Isorhamnetin and luteolin have been detected in the genus for the first time.     

Karyological studies inPelargonium sectt.Ciconium,Dibrachya, andJenkinsonia (Geraniaceae)

Pelargonium sect.Ciconium and sect.Dibrachya have a basic chromosome number of x = 9, whereas sect.Jenkinsonia has x = 9, 11, and 17.     

Aspects of floral structure and phenology in the genusConophytum (Mesembryanthemaceae)

The complex floral structure in the southern African genusConophytum (Mesembryanthemaceae; 77 spp.) is described in detail and assigned to three basic floral types, two of which can be divided into two subtypes. Correlations between structural features and phenological patterns are demonstrated and discussed in the family context as well as in relation to the systematic subdivision of the genus.     

Pollination by deceit and floral mimesis inThelymitra antennifera (Orchidaceae)

Thelymitra antennifera is found to be a general mimic of the search image of other co-blooming yellow or cream-flowered species including members of the following genera:Hibbertia, Goodenia and, to a lesser extent,Helichrysum, Pimelia andStackhousia. The most common pollinators areLasioglossum (Chilalictus) spec. and the introducedSyrphus damaster (hover fly) as well as a solitary wasp,Eurys spec.—T. antennifera acts by deceit, involving opticals (yellow colour and pollen imitation) as well as olfactory (sweet odour) signals. Capsule production is low and density dependent, a situation demonstrated in other species which have evolved pollination syndromes involving deceitful mimicry.     

Concordant clines and significant correlation between floral and pollen characters in Asarum heterotropoides var. heterotropoides (Aristolochiaceae)

To examine geographic differentiation in Asarum heterotropoides var. heterotropoides in Hokkaido Is. in the northern Japan, in which two putative cryptic species have been suspected to exist, extensive and detailed morphological research on 794 individuals from 44 populations throughout Hokkaido Is. was performed. Among the characters examined, the angle between and tip shape of the calyx lobes and the supratecta of the pollen grains were significantly correlated and were found in similar geographic clines. Among them, the pollen showed two discrete states in almost distinct distribution. Multidimensional scaling analysis showed that individuals within each of the two pollen types had different trends in flower characters. Consequently, we assumed a cline from south to north on Hokkaido Is. For the causes of the cline, the two hypotheses were proposed, primary geographic differentiation or extensive introgressive hybridization between two distinct geographical species existing in the past.     

Notes on the floral morphology in Vivianiaceae (Geraniales)

The functional floral morphology of the three genera of Vivianiaceae (= Ledocarpaceae, Geraniales), Rhynchotheca, Viviania and Balbisia, is compared. Likely pollination mechanisms are inferred from morphology and field observations. The flowers of Viviania are nectariferous and apparently zoophilous with nectar as the (primary) pollinator reward. Balbisia has pollen flowers without nectaries, its showy corolla indicates that it is also zoophilous with pollen as sole pollinator reward; bees were observed as flower visitors. One taxon (B. gracilis) may be anemophilous. Rhynchotheca has flowers without petals, with large, pendulous anthers and lacks nectaries. It shows synchronous mass flowering in its natural populations and is evidently anemophilous. A comparison with other Geraniales shows that nectar flowers with small anthers are likely the ancestral condition in Vivianiaceae. This suggests that the pollen flowers with larger anthers of Balbisia and Rhynchotheca may represent an apomorphic condition. The documentation of pollen flowers and anemophily in Vivianiaceae expands the range of known floral and pollination syndromes in Geraniales.     

Sporoderm characters ofTetrameranthus duckei (Annonaceae) and their systematic implications

Ultrastructural and micromorphological investigations of the sporoderm ofTetrameranthus duckei pollen confirm the interpretation of this genus as being isolated within theAnnonaceae.     

Reproductive biology of the genusDamasonium (Alismataceae)

The reproductive biology of the genusDamasonium was studied in cultivation and in nature. A correlation was shown between flowering time and latitude. All species are self-compatible but the N. American member of the genus (D. californicum) is strongly protandrous and probably experiences high levels of outcrossing in nature. In the European taxa the stamens and the stigmas mature simultaneously but the levels of inbreeding appear to be greater in the southern species (D. bourgeai, D. polyspermum) than in the northern (tetraploid) speciesD. alisma. The Australian memberD. minus resembles the southern European species in being strongly autogamous and bud-pollination was shown to occur. Floral morphology, stigma exertion, pollen/ovule (P/O) ratio and seed weight each show a strong correlation with the degree of autogamy. Vegetative reproduction occurs only inD. californicum andD. alisma through the production of corm-buds. This study suggests that autogamy inDamasonium is accompanied by a shift in resource allocation from male (pollen) toward female (seed) function. However, further studies are required to assess the quality of seeds and their survivorship in nature.     

The cost of selfing inEncyclia cochleata (Orchidaceae)

To determine whether inbreeding depression accounts for the maintenance of outcrossing in populations of the self-compatible orchidEncyclia cochleata, the estimated selective advantage of selfing was compared to a measure of inbreeding depression. Individuals from three populations ofE. cochleata and some of their progeny were phenotyped using isozyme analysis. The electrophoretic data were used to estimate the outcrossing rate and the theoretical cost of outcrossing. Inbreeding depression was estimated by comparing the fitness of the progeny resulting from both types of pollinations. The seeds from outcrossed and selfed hand-pollinations and naturally pollinated seeds from a population of the triandrous form ofE. cochleata were grown aseptically on culture media, and their development over the next three years recorded. Inbreeding was common, particularly in one population (outcrossing rate 40%). However, the level of inbreeding depression was only 1–2%, considerably less inbreeding depression than expected.     

Intrapopulation variation in the breeding system ofVillarsia lasiosperma (Menyanthaceae), a distylous species

The restricted perennial diploid herb,Villarsia lasiosperma, of southwestern Western Australia has distylous flowers with dimorphism in style and stamen length, stigma morphology, and pollen size. In order to assess the presence and nature of an incompatibility system in this species, a crossing program was carried out using 17 plants grown from seeds collected in two field populations. Pollen stainabilities of these plants mostly exceeded 95%. Mean seed-set of Longs following intermorph pollinations was c. 24 seeds per pollination and for Shorts was c. 16 seeds per pollination. Approximately three-quarters of the Longs and Shorts produced no seeds after self-pollination; the remainder produced very few seeds following such pollinations. No Shorts produced seeds after intramorph cross-pollinations. However, about half the Longs exhibited various levels of weakened intramorph incompatibility, with mean seed-sets following intramorph cross-pollinations up to half the mean seed-sets following intermorph pollinations. In the behavior of Longs, the incompatibility system ofV. lasiosperma differs from the idealized distylous breeding system, but resembles that of a purported close relative,V. exaltata of eastern and southeastern Australia.     

Micromorphological and phytochemical characters ofTeucrium marum andT. subspinosum (Labiatae) from Sardinia and Balearic Islands

Micromorphology and distribution of trichomes in different plant parts ofTeucrium marum andTeucrium subspinosum from Sardinia and the Balearic Islands are described. The composition of volatile compounds in the same plants has also been studied. The occurrence in Sardinia of two differentT. marum entities is evidenced. One of them, growing in the NW. part of the island, is very similar toT. marum from Minorca.T. subspinosum from Sardinia and Majorca differ for the presence in the last one of short capitate hairs and for a higher ratio of dolichodial/teucrein. While the degree of variability of all the characters is very high, there is a good homogeneity between all the taxa, due to the presence of monoterpene cyclopentanoids not found until now in other species.     

Competition between Salicornia europaea and Atriplex prostrata (Chenopodiaceae) along an experimental salinity gradient

Salicornia europaea L. is a halophyte that often occupies the lowestand most saline (>3.5% total salt) areas of salt marshes. Atriplexprostrata Boucher is less salt tolerant than S. europaea and oftengrows in a less saline (<2.0% total salts) zone adjacent to S. europaea. The purpose of this experiment was to determine thecompetitive outcome when these two species are grown at differentsalinities to ascertain the extent salinity and competition affect plantzonation. Plants were grown in a de Wit replacement series at 85, 170,and 340 mM NaCl in half-strength Hoagland's no. 2 nutrient solution fortwo months. There was a significant effect of salt concentration,competition, and their interaction on biomass production of S. europaea plants. However, only salt concentration significantly affectedbiomass production of A. prostrata plants. Results of thisexperiment confirmed the results of other studies that demonstrated thatthe more salt tolerant species were less competitive at lower salinities. Atriplex prostrata was the better competitor at 85 mM NaCl, whereasS. europaea was the better competitor at 340 mM NaClbecause growth of A. prostrata was inhibited. At 170 mMNaCl, A. prostrata biomass production decreased more than S. europaea biomass in mixed culture.     

Variation in sex ratio, morph-specific reproductive ecology and an experimental test of frequency-dependence in the gynodioecious Kallstroemia grandiflora (Zygophyllaceae)

An enduring puzzle in gynodioecious species is the great variation in female frequency seen among populations. We quantified sex ratio in 44 populations of gynodioecious Kallstroemia grandiflora. Then, we measured pollinator visitation, pollen deposition, autonomous selfing rate and pollen limitation of females. Finally, using experimental populations, we tested whether female fitness responds to the frequency of female plants. We found broad variability in sex ratio among populations (0-44% female). Hermaphrodite flowers received more pollinator visits and pollen grains than females, and bagged hermaphrodite flowers produced fruits. However, we found no evidence of pollen limitation in females. In experimental populations, female plants showed no evidence of frequency-dependent pollinator visitation, fruit set, seed set or total seed mass. These results do not support frequency-dependent variation in fitness as a major mechanism affecting female frequencies in K. grandiflora. Within the context of this study, pollinators are abundant and pollinator movement appears to operate at a large enough scale to overcome the potential reproductive disadvantages of producing solely female flowers.     

Genetic variation in the diatomFragilaria capucina (Fragilariaceae) along a latitudinal gradient across North America

Genetic variation in 126 clones of the planktonic diatom,Fragilaria capucina, collected from seven lakes from Manitoba to Texas, was determined by RAPD analysis. Five primers yielded 48 scorable RAPD fragments in 123 unique combinations. Patterns of genetic variation were analysed by cluster analysis, which showed that most clones grouped together according to the site from which they were collected. This pattern in genetic variation may be a result of the geographically disjunct nature of these populations and/or the different environmental conditions, especially temperature, in the different lakes.     

The evolutionary breakdown of distyly inLinum tenuifolium (Linaceae)

Distyly inLinum tenuifolium L. is associated with a high degree of self-incompatibility. Breakdown in this system has occurred without the morphological rearrangement expected as the result of cross-over within the distyly supergene. Pollen-flow in both distylous and monomorphic populations is leptokurtic. A high proportion of intra-flower pollination occurs. Pollen production per ovule is reduced in the self-compatible race. Mean seed-set is increased. Individuals of the self-compatible race produce less vegetative growth and require a shorter time to reach reproductive maturity under cultivation. Increased fecundity appears to provide the selective advantage promoting the breakdown of self-incompatibility in this species. This is achieved through a massive shift of resources toward female reproductive function in plants of the monomorphic race. Subsequent colonization by this race has led to its increased distribution in C. & S. Europe.