Pollination by deceit,floral sex ratios and seed set in dioecious Rubus chamaemorus L.

Summary Male and female flowers of the dioecious perennial herb Rubus chamaemorus L. are similar in general appearance. However, female flowers are somewhat smaller, do not produce any pollen, and contain very small amounts of nectar. Syrphids and bumblebees, which are important pollinators of R. chamaemorus, showed a strong preference for male flowers. Male flowers were also less often rejected by flower visitors than were female flowers, and two different groups of syrphid species stayed longer in male than in female flowers. These observations suggest that female flowers of R. chamaemorus attract pollinators by deceit.Hand-pollination experiments indicated that pollen availability limited seed production of R. chamaemorus in female dominated habitats but not in areas with an equal floral sex ratio. We suggest that the relative importance of factors limiting female reproductive success is not constant, but is influenced by the floral sex ratio of the population. This should apply also to other dioecious species that show variable sex ratios on either a local or regional scale.     

Vegetative growth and frost hardiness of cloudberry (Rubus chamaemorus) as affected by temperature and photoperiod

The effect of photoperiod and temperature on growth and induction and development of frost hardiness in cloudberry ( Rubus chamaemorus L.) was examined in two experiments. The photoperiods were 8, 12 or 24 h and the temperatures were 18, 15, 12, 9, 4, 3, –3 or –4°C depending on the experiment. The level of hardiness was expressed as LT₆₆ or LT₅₀ (the lethal temperature for 66 or 50% of the plant material) for percentage of bud break and for the degree of coloring by triphenyltetrazolium chloride for rhizomes. The vegetative growth was clearly affected by daylength; petiole elongation, leaf growth, shoot dry weight and number of shoots per plant were all reduced under short days compared with long days. However, the photoperiod had no significant effect on hardening of buds or rhizomes. Hardening increased with successively decreasing temperatures. To get the maximum hardiness, plants had to be exposed to freezing temperatures.     

Seasonal changes in frost hardiness in cloudberry (Rubus chamaemorus) in relation to carbohydrate content with special reference to sucrose

Monthly determinations of frost hardiness of cloudberry ( Rubus chamaemorus L.) buds and rhizomes were done from October 1978 to October 1979. For buds LT₅₀ (lethal temperature for 50% of the plant material) was calculated from the percentage of bud breaking and for rhizomes from visual estimations of the degree of coloring by triphenyltetrazolium chloride. The frost hardiness varied from—11.5°C in November to—4°C in May to July for buds and from—16°C in January to—3°C in June— July for rhizomes. Dehardening started in February while the plants were still covered with snow. In connection with the determinations of frost hardiness, carbohydrate analyses were done. There was a good correlation between the degree of frost hardiness and the amount of soluble carbohydrates determined with anthrone. Sucrose, determined by gas chromatography, seemed to be the sugar contributing most in this correlation.     

In vitro Propagation of Cloudberry (Rubus chamaemorus)

The purpose of this study was to establish conditions for micropropagation of cloudberry (Rubus chamaemorus L.). Cultures were initiated from meristem cultures. When cultures were subcultured from clusters of 3–5 shoots, approximately 70 and 50 shoots were produced per cluster within 6 weeks at 8.9 μM BAP for the female cv. Fjellgull and the male cv. Apollen, respectively. Addition of 5.5 μM GA₃ reduced the number of shoots. Auxins (IBA, NAA) promoted root development in vitro, but inhibited formation of new shoots. However, as much as 85% of shoots rooted without auxin treatment when planted in a peat:sand (80:20 v/v) mixture. Some of the male plants regenerated from shoot tip cultures flowered in the greenhouse within a year after transfer to soil.     

Active self-pollination in blackberries (Rubus subgen. Rubus, Rosaceae)

Most blackberry species are apomictic but pseudogamous, i.e. embryo development is dependent on prior pollination. Two different types of stamen arrangement were noted in senescing flowers of 18 Swedish species and 2 common cultivars. The stamens of 'cross-pollinating' species seldom touch the stigmas while those of 'self-pollinating' species instead arch over the pistils and dry up in this position. All species set seed well after artificial self-pollination and are thus self-compatible. Isolation experiments were carried out during 3 years. When inflorescences were bagged, seed set was drastically lowered in 'cross-pollinators' but remained almost unaltered in 'self-pollinators'. The different responses to isolation are probably due to the inherent stamen behaviour.     

Chromosome numbers of European blackberries (Rubus subg.Rubus,Rosaceae)

Chromosome numbers are presented for 32 collections of 29 European blackberry species (Rubus subg.Rubus) from Germany. One species is triploid (2n = 21), 27 species are tetraploid, (2n = 28), and one species is pentaploid (2n = 35). Chromosome numbers are reported for the first time ofR. adspersus, R. amisiensis, R. calvus, R. conothyrsoides, R. contractipes, R. demissus, R. elegantispinosus, R. ferocior, R. foliosus, R. hypomalacus, R. leucandrus, R. nemorosus, R. platyacanthus, R. praecox, R. rhombifolius, andR. rhytidophyllus. Chromosome numbers forR. dasyphyllus, R. gelertii, R. glandithyrsos, R. lamprocaulos, R. lindebergii, R. macrophyllus, R. montanus, R. muenteri, R. pedemontanus, R. polyanthemus, R. senticosus, R. silvaticus, andR. vigorosus are confirmed.     

Between-year variation in flowering and fruit set in frost-prone and frost-sheltered populations of dioecious Rubus chamaemorus

Summary The flowering and fruiting patterns of the dioecious perennial herb Rubus chamaemorus L. were studied in frost-prone (open) and frost-sheltered (Shaded) habitats in northern Sweden over 6 years. The number of ramets with flower buds, the proportion of flower buds that opened, and fruit set varied markedly between years. In the frost-prone populations, the occurrence or absence of detrimental frosts during the development of flowers and fruit could explain much of the variation, both in the proportion of flower buds that developed into flowers, and in fruit set. In the frost-sheltered populations, most female flowers that did not develop into fruit aborted without any signs of physical damage and before any ovules had begun to enlarge. Flower mortality caused by herbivores feeding on reproductive parts was commonly low, but reached values higher than 10% in one of the shaded populations. Hand-pollination increased the proportion of ovules producing seeds in the mature fruits by about 20%, and in one year also increased fruit set significantly in one population. Fruit-producing female ramets had a higher mortality and a lower probability of flowering in the subsequent year than male ramets and non-fruiting female ramets. In R. chamaemorus, the conditions for fruit maturation are highly unpredictable at the time of flower initiation. It is suggested that the apparent over-initiation of flower buds is advantageous, as it allows the plant to attain a high reproductive success in years favourable for flowering and fruit development.     

Apomixis versus sexuality in blackberries (Rubus subgen.Rubus,Rosaceae)

InRubus L. a connection seems to exist between the degree of meiotic disturbances on the one hand, and the production of unreduced embryo sacs, pollen fertility and relative seed set on the other hand. Severe meiotic disturbances commonly encountered in apomictic taxa decrease pollen fertility and thereby seed set since pollen is necessary for endosperm development. By contrast interspecific hybrids between apomictic taxa appear to be sexual and exhibit high pollen fertilities, probably due to an improved meiosis. Thus, apomixis leads to a decreased fertility inRubus, not the opposite, as often discussed.     

DNA fingerprint variation in some blackberry species (Rubus subg.Rubus,Rosaceae)

We have analysed samples from Sweden, Denmark, and Germany of six facultatively apomictic blackberry species to investigate the accordance between a taxonomy based on morphological characters on the one hand, and distribution of genetic variation estimated by DNA fingerprinting on the other hand. DNA fingerprint variation was found to be quite restricted in all species investigated. The first taxonomic group included three species related toRubus nessensis, two being characterized by one very widespread DNA fingerprint in all three countries and a few rare ones, whereas the third species differed between Sweden and Germany. The second taxonomic group included species related toR. gracilis. Two of these species exhibited very similar DNA fingerprints, whereas the third species deviated clearly. The utilization of DNA fingerprinting as a tool in taxonomy is discussed; most likely this method could become a useful complement to morphology, especially in plant groups with reduced levels of genetic recombination.     

钻地风的三萜类成分

从钻地风根的乙醇提取物中分离得到12个三萜及三萜皂苷类化合物,通过波谱分析并与有关对照品比较, 其结构鉴定为熊果酸(1),坡模酸(2),tormentic acid (3),蔷薇酸(4),sericic acid (5),23-hydroxytormentic acid (6), kaji-ichigoside F1 (7),野蔷薇苷 (8), sericoside (9), quadranoside VIII (10), crataegioside (11)和niga-ichigoside F1 (12).初步研究结果表明,这些化合物在体外5?mg/ml浓度下对耐药金黄色葡萄球菌(MRSA)无抑制作用.     

A demographic study of the apomictic blackberry, Rubus nessensis (Rosaceae)

Ten stands of Rubus nessensis , an apomictic blackberry, were studied. Perennial stools produce biennial shoots that flower in their second year. The stools tend to produce shoots of similar height for several consecutive years. Flowering, but not relative fruit set, is dependent on shoot height. Shoot height and density appear to be positively related, implying that intraspecific competition is of little importance for plant vigour. Depletion time varies greatly between stands (4–29 years), being comparatively longer in stands with short shoots. New establishment is sparse and takes place mostly by root suckering.     

Pollen stainability variation in the apomictic blackberry, Rubus nessensis (Rosaceae)

Pollen quality was assessed with cotton blue staining in an apomictic blackberry, Rubus nessensis W. Hall, on plants grown outdoors in a random arrangement under uniform conditions. Significant variation between populations may be attributed mainly to genetical factors. Most of the variation found between plants, sometimes even between ramets, within a population must, however, be environmentally caused, likewise the variation between flowers within the same plant.     

Cytotoxic,hypoglycemic activity and phytochemical analysis of Rubus imperialis (Rosaceae)

Rubus imperialis, Artemia salina, 3-O-methylellagic-4'-O-alpha-rhamnose Acid Screening of different extracts, fractions and compounds from Rubus imperialis Chum. Schl. (Rosaceae) has been conduced using the brine shrimp microwell cytotoxicity assay. Three parts of the plant (methanolic extract from leaves, roots and stems), three fractions from roots (hexane, ethyl acetate and butanol) and three isolated compounds (niga-ichigoside F1, 23-hydroxytormentic acid, ellagic acid derivative) were tested. The most promising material (LC50 <1000 microg/ml) were the methanolic extract and ethyl acetate fraction from roots. However, there was little correlation observed in the degree of toxicities observed between the isolated compounds. On the other hand, the cytotoxicity and in vivo assays confirmed the hypoglycemic activity of methanolic extract and validated the Brazilian popular use of R. imperialis as an antidiabetic agent.     

Rubus vestervicensis (Rosaceae) — its hybrid origin revealed by DNA fingerprinting

Kraft, T., Nybom, H. & Werlemark, G. 199.5. Rubus vestervicensis (Rosaceae) — its hybrid origin revealed by DNA fingerprinting. — Nord. 3. Bot. 1.5: 237–242. Copenhagen. ISSN 0107-055X.
The large number of species in Rubus subgenus Rubus are thought to have arisen, at least in part, through hybridiation between facultatively apomictic species. R. vestervicensis is known only from a small island off the Swedish east coast. It has been suggested that it is a hybrid between R. grabowskii and R. pedemontanus . We have compared these species with DNA fingerprinting and our results support the hybridization hypothesis. All bands found in the fingerprint of R. grabowskii and about half of the bands found in R. pedemontanus were present in R. vestervicensis , suggesting that the latter species was derived from fertilization of an unreduced R. grabowskii egg cell with R. pedemontanus pollen.     

Rediscoveries of two species of Rubus (Rosaceae) in China

报道了蔷薇科两种悬钩子属植物在中国的重新发现,分别为美叶悬钩子(Rubus calophyllus C.B.Clark)和拟针刺悬钩子(R.parapungens H.Hara),并提供了简要的描述和标本照片.     

Photosynthetic characteristics of invasive and noninvasive species of Rubus (Rosaceae)

The prolific amount of growth and reproduction in invasive plants may be achieved by greater net photosynthesis and/or resource-use efficiency. I tested the hypotheses that leaf-level photosynthetic capacity and resource-use efficiency were greater in two invasive species of Rubus as compared with two noninvasive species that have overlapping distributions in the Pacific Northwest. The invasive species had significantly higher photosynthetic capacity and maintained net photosynthesis (A) over a longer period of the year than the noninvasive species. The construction cost (CC) of leaf tissue per unit leaf mass was comparable among the four species, but the invasive species allocated less nitrogen (N) per unit leaf mass. On a leaf area basis, both leaf CC and N were higher for the invasive species. The specific leaf area (SLA) was also lower in the invasive species, indicating less photosynthetic area per gram leaf tissue. The invasive species achieved high A at lower resource investments than the noninvasive species, including having higher maximum photosynthetic rate (A(max)) per unit dark respiration (R(d)), greater A(max) per unit leaf N (photosynthetic nitrogen-use efficiency), and greater water-use efficiency as measured by instantaneous rates of A per unit transpiration (A/E) and by integrated A/E inferred from stable carbon isotope ratios (δ(13)C). Using discriminant analysis, these photosynthetic characteristics were found to be powerful in distinguishing between the invasive and noninvasive Rubus. A(max) and A/E were identified as the most useful variables for distinguishing between the species, and therefore, may be important factors contributing to the success of these invasive species.     

Rubus ambrosius (Rubus subsect.Rubus, Rosaceae), a new bramble species from the eastern part of Central Europe

Rubus ambrosius Trávní?ek etOklejewicz, a widely distributed species from the eastern part of Central Europe (Czech Republic, Slovakia and Poland), is described.R. ambrosius differs from similar speciesR. sulcatus Vest by more deeply furrowed stems, longer prickles on first-year tems, longer petioles, more prickly petioles, densely hairy leaves beneath and by blunter leaf margin serration with incisions only (2-)1.5–2.5 mm deep. The newly described species is illustrated both by photographs (including the holotype) and a line drawing. A list of localities and a distribution map are presented.     

Rubus canduliger, a new regional species from the Netherlands, with notes on the range structure and dynamics of brambles (Rubus, Rosaceae)

Rubus canduliger is described as a new regional bramble species belonging to the seriesDiscolores. It has been recognized in the Netherlands as a distinct species for more than 70 years but identified as the central EuropeanR. grabowskii. The latter, however, differs by its tapering prickles, regular leaves with longer petiolule of the terminal leaflet, broader, often pyramidal inflorescence, and white or pink flowers with carpels hairy at the top.R. canduliger has a well-defined range north of the Rhine river around Arnhem where it occurs in urban and other disturbed habitats. Historical events, e.g. transport of young trees in the 16th century may explain most records south of the Rhine river, 25–50 km outside the main range. The ecology and phytosociology of the new bramble are discussed. Its distribution is compared toR. trichanthus, another regional species with a similar range asR. canduliger, but occurring in more natural habitats. In pseudogamous European blackberries (Rubus sectionRubus =R. fruticosus agg.), range size is considered to be related to the age of the species. Several widespread species have disjunct distribution ranges that are suggested to be the result of long-distance dispersal by migratory birds but unintentional anthropogenic transport of seeds may be involved as well. We hypothesize that in northwestern Europe fragmentation of continuous ranges of widespread species was caused by ongoing deforestation and subsequent degradation (acidification) of originally base-rich sandy and loamy soils from the Iron Age onward. Many regional species, however, have originated and spread in the resulting man-made landscapes. A classification of range types of brambles differing in size and internal structure is presented.     

Taxonomy and distribution of the genus Rubus (Rosaceae) series Radula on the Iberian Peninsula

Monasterio-Huelin. E. 1995. Taxonomv and distribution of the genus Rubus (Rosaceae) series Radulu on the Iberian Peninsula. — Nord. J. Bot. 15: 365–373. Copenhagen. ISSN 0107–055X.
The majority of european batologists currently interpret the ser. Radula in a sense different from that given by its original author. According to the modem concept, this series is separated into two, distinguished by the leaflets felted beneath (ser. Radula ) versus not felted (ser. Pallidi ). Following this criterion, we include 7 species in ser. Radula , one of which ( R. pauanus ) is described as new, and provide a photograph of the holotype, an analysis of pollen, and a distribution map. Also provided are keys to the series of the subgenus Rubus and to the species of the ser. Radula , and a comparative study from a morphological and biogeographical perspective of all species which comprise this series on the Iberian Peninsula.