Floral Clusters Research Articles

Calamus longipinna (Arecaceae: Calamoideae) and Its Relatives in New Guinea

Summary. The taxonomy and morphology of the Calamus longipinna (Arecaceae) group is revised and discussed. This group of rattan species from New Guinea and the Solomon Islands is defined by the possession of a distinctive, inflated ocrea at the mouth of the leaf sheath and rather uniform A striking feature of the New Guinea species of the rattan genus Calamus is the frequent presence of elaborate ocreas. The ocrea is widespread in some other rattan genera, namely Korthalsia, Plectocomiopsis, Laccosperma, Eremospatha and Oncocalamus. In most cases, the structure is merely a low, inconspicuous, tubular extension of the leaf sheath above the insertion of the petiole. However, in some species of Calamus, Korthalsia and Laccosperma, the ocrea is enlarged, highly conspicuous and widely variable in morphology. For example, some ocreas are inflated and clasp the stem or diverge from it at an acute angle. Ants often colonise inflated ocreas, cultivating scale insects for honeydew on the leaf sheaths and aggressively defending their home, and, at the same time, the rattan (Dransfield 1979). In a few species of Korthalsia and one species of Calamus, the ocrea consists of a reticulum of fibres which is tightly adpressed to the sheath or else expands into an open funnel. A number of Calamus species (e.g. C. paspalanthus Becc. in west Malesia and C. zebrinus Becc. in New Guinea) possess greatly enlarged ocreas, sometimes as long as 1 m or more, that disintegrate and fall not long after emergence. Approximately 14 species of Calamus in New Guinea possess such enlarged ocreas. The C. longipinna Lauterb. & K. Schum. group, the subject of this paper, is characterised by its inflated ocreas that clasp the stem and a characteristic yet rather simple flagelliform inflorescence morphology. The group is distinguished from the ocreate species related to C. macrochlamys Becc. and C. zebrinus Becc. because it does not possess the unusual floral cluster architecture that is so remarkable in this group (Dransfield & Baker, submitted). Calamus humboldtianus Becc. is not included in the C. longipinna group because it bears bizarre inflorescences with congested branches as well as unusual leaf and ocrea morphology. The fibrous, fragile ocrea and robust rachillae of C. klossii Ridl. set it apart from other New Guinea ocreate rattans. Calamus distentus Burret may yet prove to be a relative of the C. longipinna group, but the ocrea diverging from the stem and very slender inflorescence morphology are not congruent with such a placement.

Floral patterns in the California Current System off southern California: 1990-1996

In 1990, CalCOFI cruises began routine collection of samples for the enumeration of phytoplank-ton species. From each quarterly cruise, nearsurface samples from 34 stations are pooled into four regional samples prior to counting. This paper summarizes the first 6.5 years of the program in order to identify major large-scale patterns of species composition and fluctuations. A total of 312 species were recognized during this study. Recurrent group analysis defines two major floral clusters. The first is composed of diatoms characteristic of enriched regions. This cluster is most abundant in the northeastern region and often attains maximum abundances in the spring. Seventy-two percent of the variability of chlorophyll is accounted for by the variability of these species. The second cluster is composed of species common in the offshore central North Pacific. These species have relatively low spatial and temporal variability in the study region. There is no detectable seasonality. In neither cluster can interannual variability be detected above seasonal variability, spatial variability and error. These patterns differ from the geographic patterns of zooplankton species in the region, which are often dominated by fauna from the subarctic North Pacific and transition zone. The apparent absence of a similar subarctic flora is briefly discussed.

The Arabidopsis compact inflorescence genes: phase-specific growth regulation and the determination of inflorescence architecture.

During their life cycle, higher plants pass through a series of growth phases that are characterized by the production of morphologically distinct vegetative and reproductive organs and by different growth patterns. Three major phases have been described in Arabidopsis: juvenile vegetative, adult vegetative, and reproductive. In this report we describe a novel, phase-specific mutant in Arabidopsis, compact inflorescence (cif). The most apparent aspect of the cif phenotype is a strong reduction in the elongation of internodes in the inflorescence, resulting in the formation of a floral cluster at the apical end of all reproductive shoots. Elongation and expansion of adult vegetative rosette leaves are also compromised in mutant plants. The onset of the cif trait correlates closely with morphological changes marking the phase transition from juvenile to adult, and mutant plants produce normal flowers and are fully fertile. Hence the cif phenotype appears to be adult vegetative phase-specific. Histological sections of mutant inflorescence internodes indicate normal tissue specification, but reduced cell elongation compared to wild-type. compact inflorescence is inherited as a two-gene trait involving the action of a recessive and a dominant locus. These two cif genes appear to be key components of a growth regulatory pathway that is closely linked to phase change, and specifies critical aspects of plant growth and architecture including inflorescence internode length.

Epigenetical variability of the unianthy and synanthy expression in sugarbeet

The two loci model of unianthy-synanthy character inheritance in sugarbeet is analysed in paper (the Mm and li loci). According to this model the MMii and Mmii genotypes of plants form on the floral shoots and clusters consisted of 3-5 flowers, and the mmii genotype of plants consisted of 2-3 flowers correspondingly. All the three genotypes were synanthous (SA) phenotype and form the multigerm sowing units. Unianthous (UA) plants initiate the separate (single) flowers and fruits on floral shoots and their genotype was mmll or mmli. We’ve studied the non-stability of the UA-character expression when UA plants are self-reproduced. It was demonstrated this non-stability is based on the epigenetic inactivation of dominant alleles (I = I0) of the inhibitor locus. One of the reason to cause the inactivation of inhibitor allele could probably be rather high level of polysomaty in the cell populations of UA inbred lines. The experimental rising of the quota of endopolyploid cells leads to unianthous plants transformation into the synanthous ones.

Stomatal and Chlorophyll Distribution of Cox's Orange Pippin Apple Flowers Relative to Other Cluster Parts

Surface area, chlorophyll concentration and stomatal size and density were measured for all green components of floral clusters on Cox's Orange Pippin apple trees to assess their relative potential for photosynthesis. Before flower opening, sepals and receptacles had chlorophyll concentrations similar to those found in the laminae of rosette leaves. But, whereas the concentration in rosette leaves continued to increased until fruit set, those in the sepals and receptacles decreased.Sepals had a greater mature stomatal density than leaf laminae shortly after bud burst; although both densities increased, that on the laminae later exceeded that on sepals.Flowers contributed significantly to the green surface are (40%), chlorophyll content (30%) and mature stomatal number (25%) of floral clusters at the green cluster stage, but these contributions then decreased. Cox apple flowers appear to have the potential for contributing significantly to their carbohydrate requirement at a time when the rosette leaves are not thought to be exporters of photosynthate.

The development of fruit shape in kiwifruit: Growth characteristics and positional differences

The distribution of normal and aberrant shaped flower buds and floral clusters was examined for a sample of kiwifruit vines. Normal, flat and fan shaped flowers, and floral clusters were described relative to their position along a lateral shoot and to the position of the shoot along a cane. The total number of flowers was greater on lateral shoots at more distal regions of the cane than on proximal shoots. The proportionate number of flat and fan shaped buds was similar among all but the most proximal lateral shoots on the cane. No flower was found distal to the nine proximal nodes of a lateral shoot. Flat and fan shaped flower buds were maximal at nodes 3 and 1 of the lateral shoot respectively. Possible pathways by which fans and floral clusters may arise are discussed. Growth of normal and flat fruit was compared from anthesis to maturation. There was no significant difference in relative rates of increase in length or in maximum and minimum diameters between the two fruit types. The evolving shape of...

White sapote (Casimiroa edulis): performance under various culture salinities and environmental stress conditions in field studies

White sapote (Casimiroa edulis) has recently been introduced into the Negev Desert of Israel. Its tolerance to salinity was studied in a short-term sand culture experiment. One-year-old seedlings were irrigated with nutrient solutions of varying NaCl content (electrical conductivity of 1.5 (control), 4, 8 or 12 dS m−1). The increase in shoot length and truck circumference fell to 50% of the control at 4 dS m−1 and to 5–7% of the control at 8–12 dS m−1. Leaves showed damage only at 12 dS m−1. Elevated salinity raised Cl and Na and depressed K concentrations (dry weight basis) in roots and shoots. Concentration of Cl in stems and leaves of salt-stressed plants increased more rapidly than that of Na. Data are also presented on the performance of seedlings planted at three sites in the Negev Desert differing in climate and water quality as follows: Besor — moderate temperatures and good quality water; Ramat-Negev — low winter tempertures (minimum of −7°C) and good quality water; Qetura — high summer temperatures (up to 46°C) and brackish water (4.0 dS m−1). Growth of 3.5-year-old trees in terms of trunk circumference was 1.6 and 1.2-times more vigorous at Besor than at Ramat-Negev and Qetura, respectively. Trees accumulated more Cl in stems and leaves at Qetura than at other sites, although no stress symptoms were observed on leaves. Significant production of floral clusters started in the fourth year and was weakest at Ramat-Negev and most abundant at Qetura.

Prodiplosis longifila (Diptera: Cecidomyiidae) a New Pest of Citrus in Florida

In the fall of 1984 excessive flower drop was observed in lime Citrus aurantifolia (Christm.) Swingle trees in the vicinity of Homestead, Dade Co., Florida. In a preliminary survey, two lime groves were sampled on the 13th and 25th of October 1984. Sampling consisted of randomly selected collections of floral clusters from 20 trees on each date. Prodiplosis longifila (Gagne) larvae were collected for the first time from lime flowers. Larvae were observed feeding on the style, ovary and filaments. After larval injury, the flowers bore symptoms of fungal infection characterized by necrosis of the ovary and calyx. P. longifila has been reported feeding on wild cotton Gossypium hirsutum L. in Florida (Rainwater 1934) as Cantarinia gossypii (Felt), and is also known to attack alfalfa Medicago sativa L., beans Phaseolus vulgaris L., tomatoes Lycopersicon esculentum L. and potatoes Solanum tuberosum L. in Peru (Gagne 1986). A survey of arthropods associated with lime flowers was conducted on March 20 and March 27, 1985 to establish whether a relationship exists between P. longifila infestation and flower damage. Lime flowers were obtained from commercial lime groves in Dade County, Florida. Clusters of flowers were randomly selected, picked, and transported to the laboratory for examination, where the flowers were opened and examined for the presence of arthropods. Eighty-five percent of 270 lime flowers analyzed contained P. longifila larvae (Chisquare: X2 o5[4] = 9.48) and 11% contained Polyphagotarsonemus latus Banks (Acarina:Tarsonemidae). Species of Hymenoptera were present in 2% of the flowers and Homoptera and Thysanoptera were present in 1% of the flowers. C. sinensis (L) Osb., C. aurantifolia, C. limon (L.)., C. volkaneriana (Ten. & Pasq.) and C. grandis (L.) were sampled for P. longifila March 20, and March 27, 1985 in the 1.37 ha Citrus germplasm collection of the University of Florida Tropical Research and Education Center. Sampling consisted of randomly selected floral clusters from 2 trees for each Citrus species and date. From 20 inflorescences collected for each Citrus species, more C. aurantifolia (1250%) flowers were infested with P. longifila larvae than were C. sinensis, var. Valencia (7%), C. grandis (0%), and C. volkaneriana (0%). Sixty lime flowers infested with P. longifila larvae were dissected and the stamens, ovary, and petals were separated. The petals, stamens and ovary were dipped in Tween 20R (1 drop/50 cc), rinsed in running water for 20 min, disinfected with 95% ethanol for 5 seconds, aseptically cut and then plated out on pH 5.6 potato dextrose agar (PDA). These plates were examined for evidence of fruiting structures after 10 days. Three different isolates were obtained: Cladosporium herbarum LK. ex Fr. var. citricola Farl., Colletotrichum gloesporoides Penz and Penicillium sp.. Infection of Citrus flowers by all or any one of these fungi can cause premature fruit drop. Feeding by P. longifila causes wounding which may play an important role in fungal infection of blossoms and subsequent development of flower rot. Similar type of disease induction with cotton flowers has been previously correlated with feeding by another Cecidomyiidae, Cantarinia gossipii in South America (Jimenez & Ramirez 1984). Symptoms of Colletotrichum infection on the ovary and stamens, where P. longifila feeding occurs differs from other bloom infections,

The himalayan grain chenopods: Floral variations and their role in seed formation

Four Himalayan chenopod cultivars (Chenopodium album L.) were investigated for their floral morphology and its possible role in seed formation. The gynomonoeicious plants bear three basic flower types viz., hermaphrodite, chlamydeous female and achlamydeous female which were further divisible into five types on the basis of their position, morphology and size. The proportion of these flower types in the floral clusters was found to be dependent on the location of a cluster in the inflorescence. Each inflorescence contained an average of 33% flowers that produced viable seeds, the rest being abortive. Implications of these results in seed polymorphism and crop agronomy of chenopods are also discussed.