The flavonoids of Stenosiphon (Onagraceae)

Stenosiphon linifolius is a monotypic genus of the tribe Onagreae of the Onagraceae. The species is widespread in, but restricted to, the Great Plains of the United States. Three flavonol glycosides, kaempferol 3-O-rhamnoside, quercetin 3-O-rhamnoside and myricetin 3-O-rhamnoside, were found to occur in methanolic extracts of Stenosiphon leaves. Similar compounds are found in the leaves of such related genera as Oenothera and Gaura, but in the latter genera, additional flavonols exhibiting greater substitutional variation also are found.     

Sulphatides and pollination in Oenothera missouriensis

Analyses of the sulphatides in the pollen and style of Oenothera missouriensis show that these membranous lipids are comparatively less important in the styles than in the pollen. Incompatible pollination is followed by a large increase in sulphatides, whereas cross-pollination also causes an increase in sulphatide but to a much lesser extent. This mobilization of sulphatides in the membrane is discussed in term of permeability.     

翼茎水丁香,中国大陆柳叶菜科一归化水生植物

首次报道了在江西省南昌市南昌县与进贤县发现的柳叶菜科原产美洲一归化种:翼茎水丁香(Ludwigiadecurrens Walt.),茎具翼,蒴果方柱形,特征明显,易与国产同属植物区分。对其特征和生境信息进行了描述,并简要讨论了其潜在的入侵风险。     

The absence of cryptic self-incompatibility in Clarkia unguiculata (Onagraceae)

Many species exhibit reduced siring success of self-relative to outcross-pollen donors. This can be attributed either to postfertilization abortion of selfed ovules or to cryptic self-incompatibility (CSI). CSI is a form of self-incompatibility whereby the advantage to outcross pollen is expressed only following pollinations where there is gametophytic competition between self and outcross pollen. Under the definition of CSI, this differential success is due to the superior prefertilization performance (pollen germination rate and pollen tube growth rate) of outcross pollen relative to self pollen. Although CSI has been demonstrated in several plant species, no studies have assessed among-population variation in the expression of CSI. We conducted a greenhouse study on Clarkia unguiculata (an annual species with a mixed-mating system) to detect CSI, and we compare our observations to previous reports of CSI in C. gracilis and another population of C. unguiculata. In contrast to these previous studies of CSI in Clarkia, we used genetic rather than phenotypic markers to measure the relative performance of selfed vs. outcross pollen. In this study, we measured the intensity of CSI in C. unguiculata from a large population in southern California and we determined whether the magnitude of pollen competition (manipulated by controlling the number of pollen grains deposited on a stigma) influenced the outcome of competition between self and outcross pollen. In contrast to previous investigations of Clarkia, we found no evidence for CSI. The mean number of seeds sired per fruit did not differ between self and outcross pollen following either single-donor or mixed pollinations. In addition, the relative success of selfed vs. outcross pollen was independent of the magnitude of pollen competition. These results suggest that: (1) one of the few nonheterostylous species previously thought to be cryptically self-incompatible is completely self-compatible (at least in the population studied here) or (2) phenotypic markers may be problematic for the detection of CSI.     

A comparison of venation pattern development in wild type and a homeotic sepaloid petal mutant of Clarkia tembloriensis (Onagraceae)

Vascular system development in sepals, petals, and sepaloid petals was compared in wild-type and crinkled petal mutant plants of Clarkia tembloriensis. Patterns of vascularization in cleared whole mounts were visualized and traced under both brightfield and polarizing illumination. Wild-type sepals exhibited a basipetal pattern of maturation, with tracheary elements maturing relatively rapidly. Mature sepals had three primary veins with numerous secondary veins. In contrast, wild-type petals exhibited an acropetal pattern of maturation, with tracheary elements maturing relatively slowly. The mature petals had only one primary vein with numerous secondary veins. Sepaloid (crinkled) petals combined characteristics of both wild-type sepals and wild-type petals. They exhibited a basipetal pattern of development and a relatively rapid maturation of the tracheary elements characteristic of wild-type sepals. Venation architecture in crinkled petal mutants showed a single primary vein with numerous secondary veins, similar to wild-type petals. The crinkled petal mutant fits the definition of a homeotic mutant in that the petal has assumed characteristics of the sepal. However, homeotic transformation from petal to sepal is incomplete since the crinkled petal still retains many of the characteristics of wild-type petals.     

The status of Clarkia australis (Onagraceae)

Clarkia australis and C. virgata grow on the western slope of the central Sierra Nevada of California. Clarkia australis was established to accommodate populations of C. virgata from south of the Tuolumne River that could not be successfully hybridized to populations north of the river. Although the species is maintained in the new Jepson Manual, its validity has been questioned because only two populations were originally tested, and they had no useful morphological traits that distinguished them from C. virgata. We report here the results of a large program of interpopulation hybridizations that show that C. australis is distinct and that its reproductive isolation from C. virgata is complete and absolute and reflects a compatibility block that apparently causes abortion of hybrid seeds in early development. Both species include populations north and south of the Tuolumne River and, in general, those of C. australis occupy higher elevations. Morphologically, the species are extremely similar though the mean values of several dimensions of the petals are different. However, significant variation among their populations has the consequence that, at present, the only certain way to assign particular populations to species is to test their compatibility with previously tested populations.     

Glycoflavones in Circaea

Hydrolysates of methanolic leaf extracts of Circaea yield the glycoflavones vitexin, isovitexin, vicinin-1, and vicinin-2. Additional flavonoids are found in the unhydrolyzed extracts. Previous studies of Onagraceae report only flavonols and one chalcone. Circaea is assigned to a monogeneric tribe of Onagraceae and has no clear relationship to any other group within the family. The presence of glycoflavones in Circaea serves to underscore the distinctiveness of the genus.