Synflorescences of Malvaceae

Application of the synflorescence concept provides a precise terminology to describe homologous inflorescence structures of Malvaceae. The synflorescences of Malvaceae are generally polytelic, but terminal flowers occur as rare exceptions, which are likely to represent reversals and might be comparable to cases known in Arabidopsis or Antirrhinum . The florescences are composed of cymose partial florescences that exhibit a specific structure: their first prophyllar node may bear a lateral, originally vegetative monopodial shoot; the second prophyll may subtend a sympodium of one-flowered modules. The number of flowers is variable, but even in one-flowered partial florescences the lateral vegetative bud is usually present. In most species the prophylls and internodes within the partial florescences are reduced. Other variations of the basic type include condensation of florescences and the occurrence of accessory buds in partial florescences.     

The inflorescence in Commelinaceae

The structure of the synflorescence and the flowering unit (inflorescence) in Commelinaceae are characterized. The synflorescence is polytelic and the basic inflorescence type is a terminal pedunculate thyrse with an indeterminate central axis to which several to many cincinni are attached. Each thyrse is a florescence, and each cincinnus is a partial florescence. Variations mainly in the number of cincinni and in the number of flowers on each cincinnus determine the main differences found in the inflorescences of the different genera. Hypothesized developmental processes are described, with a view to finding relationships among different models characterized in the family as well as defining characters for cladistic studies, which may be useful to depict all the variations observed and serve as a guide for future phylogenetic studies.     

Early inflorescence and floral development in Cocos nucifera L. (Arecaceae: Arecoideae)

Palms are generally characterized by a large structure with a massive crown that creates difficulties in anatomical studies. The flowering behaviour of palm species may be a useful indicator of phylogenetic relationships and therefore evolutionary events. This paper presents a detailed histological study of reproductive development in coconut (Cocos nucifera L.), from initiation up to maturation of staminate and pistillate flowers. Reproductive development in coconut consists of a sequence of individual events that span more than two years. Floral morphogenesis is the longest event, taking about one year, while sex determination is a rapid process that occurs within one month. The inflorescence consists of different ultimate floral structural components. Pistillate flowers are borne in floral triads that are flanked by two functional staminate flowers. The staminate flowers are born in floral diads towards the base of the rachilla followed by solitary flowers in the middle to top of the rachilla. Three primary phases were identified in reproductive development, namely, transition of axillary bud into inflorescence bud, formation of floral buds, and sexualisation of individual flower buds. All developmental events with respect to stage or time of occurrence were determined.     

Una nueva especie de <Emphasis Type="Italic">Pseudomiltemia</Emphasis> (Rubiaceae) de Chiapas,México

Pseudomiltemia davidsonii is described and illustrated as a new endemic species from the Sierra Madre of Chiapas, Mexico. It is a shrub or small tree characterized by having flowers axillary and solitary or in monochasia and with large yellow corollas. Pseudomiltemia davidsonii differs from P. filisepala, the only other species in this genus, by its opposite leaves with longer petioles, inflorescences with shorter peduncles 5–13 mm long, smaller bracts, longer pedicels 6–15 mm long, and narrower fruits 3.5–4.5 mm in diameter.     

Revision of Maranta subgen. Maranta (Marantaceae)

Maranta subgen. Maranta includes species related to M. arundinacea L. It is characterized by aerial shoots with a strong monopodial tendency, absence of root tubers, simple inflorescences or few-branched, often diffuse synflorescences, florescences with few, herbaceous spathes, and comparatively large, distinctly pedicellate flowers. There are occasional exceptions to all these characters. Most species are partial selfers, only two or three being allogamous. Sixteen species are recognized, eight of which are new: M. linearis, M. sobolifera, M. lindmanii, M. zingiberina, M. incrassata, M. rupicola, M. amazonica , and M. tuberculata. The new species are described, and all species are defined and discussed, data being given about distribution and habitat. Growth habit and rhizome structure are essential taxonomic characters, but leaf shape and indument distribution are more useful characters for routine identification. Of the species referred to subgen. Automaranta by Schumann in Das Pflanzenreich, three are excluded: M. cordata, M. pohliana , and M. foliosa.     

New species of <Emphasis Type="Italic">Pleonotoma</Emphasis> (Bignonieae,Bignoniaceae) from Amazonia,Brazil

Two new species of Pleonotoma Miers (Bignonieae, Bignoniaceae) from Brazilian Amazonia are described and illustrated: Pleonotoma fissicalyx B. M. Gomes & Proen?a and P. longiflora B. M. Gomes & Proen?a. P. fissicalyx is characterised by foliaceous prophylls of the axillary bud, 3-ternate leaves, a large number of short racemes concentrated at the apex of the flowering branch with many visible pedicel scars, a laterally fissured, almost spathaceous calyx, and a small, narrow hypocrateriform corolla with subexserted anthers; the fruits are unknown. P. longiflora is characterised by the combination of weakly tetragonal branchlets with unribbed angles, non-foliaceous, flat, rounded prophylls of axillary bud with an eccentric tip, 2-ternate leaves, broad axillary racemes, an elongate tubular calyx and a hypocrateriform corolla up to 12 cm long; its inclusion within Pleonotoma is confirmed by molecular phylogeny.     

Vascular and General Anatomy of the Rootstocks of Three Stemless Viola Species

The primary vascular system of the rootstock of Viola rotundifolia,V. odorata and V. cucullata consists of an open system of threesympodia, corresponding to three orthostichies (parastichies)of leaves in the 1 /3 phyllotaxy. Between the major, collateralbundles there are vascular strands consisting of only primaryphloem. The vascular supply to axillary buds developing in thefirst season of growth is the same in flowering and vegetativebuds and there is a homology between the bracts on the pedunclesof axillary flowers and the prophylls of the axillary vegetativebranches. The overwintering portions of the rootstocks are somewhatwoody. The uneven development of secondary xylem correspondsto the locations of the sympodia. Secondary xylem closes a leafgap of a median trace only slowly, but any gap in the phloicsystem is closed quickly by secondary growth. Viola rotundifolia, V. odorata, V. cucullata, rootstock, vascular anatomy     

Foraging behavior of three bee species in a natural mimicry system: female flowers which mimic male flowers in Ecballium elaterium (Cucurbitaceae)

Summary The behavior of Apis mellifera and two species of solitary bees which forage in the flowers of monoecious Ecballium elaterium (L.) A. Rich (Cucurbitaceae) were compared. The female flowers of E. elaterium resemble male flowers visually but are nectarless, and their number is relatively smaller. Apis mellifera was found to discriminate between the two genders and to pay relatively fewer visits to female flowers (mean of 30% relative to male flowers) from the beginning of their activity in the morning. The time spent by honeybees in female flowers is very short compared to that spent in male flowers. It is surmised that the bees remember the differences between the flowers where they foraged on the previous days. In contrast, the two species of solitary bees Lasioglossum politum (Morawitz) (Halictidae) and Ceratina mandibularis Fiese (Anthophoridae) visit the female flowers with nearly equal frequencies at the beginning of each foraging day and stay longer in these flowers. Over the day there is a decline in the relative frequency of visits to female flowers and also in the mean time spent in them. The study shows that bees can collect rewards at high efficiency from the flowers of Ecballium elaterium because of their partial discrimination ability and the scarcity of the mimic flowers. It is suggested that the memory pattern of some solitary bees may be different from that of Apis mellifera. It seems that the limited memory and discrimination ability of bees can lead to a high frequency of visits to the mimic flowers during a long flowering season.     

Organographic and ontogenetic studies on the inflorescence ofLespedeza cuneata (Dum.-Cours.) G. Don (Leguminosae)

Structure of inflorescence and its variation were organographically and ontogenetically studied inLespedeza cuneata (Dum.-Cours.) G. Don. An axillary inflorescence of the species forms a compound inflorescence which is composed of three or four component inflorescences. Each component inflorescence bears four (rarely six), three, two, or one flowers. Based on the arrangement of inflorescence phyllomes, the component inflorescence with four flowers is interpreted as a pseudoraceme bearing two shortened lateral shoots (partial inflorescences) each of which has two flowers. The component inflorescence with one flower appears to be terminated by the flower and to compose the cyme. Organographic observations revealed that the terminally located flower is not truly terminal, but axillary in origin. Ontogenetic observations showed that the apices of component inflorescence and partial inflorescence exist in early developmental stages in spite of variation in the form of component inflorescence. The terminally located flower in the cyme-like inflorescence was thus demonstrated to be laterally borne on the partial inflorescence axis. The component inflorescence composing the cyme-like one inL. cuneata is a reduced form in the number of partial inflorescences and of flowers from the pseudoraceme. The cyme-like inflorescence inL. cuneata resembles the inflorescence ofKummerowia.     

In vitro floral induction from thin longitudinal sections and micro-cuttings of juvenile cork oak material

In vitro flowers were obtained from thin longitudinal sections excised at the proximity of the apical region or nodal regions of the main stem and axillary shoots of in vitro Quercus suber stock shoots as well as from field-grown seedlings. In vitro floral induction was also achieved from nodal segments of 8- to 9-month-old seedlings or from micro-cuttings of embryonic main shoot and its axillary shoots of 2-month-old seedlings. The more juvenile the material the shorter the period required to achieve flowering. Under the described experimental conditions we have thus been able to induce the expression of neoteny in a woody, long-cycle species such as cork oak.     

Two new species of Myrtaceae (Myrteae) from northern South America

Two new species of Myrtaceae are described and illustrated. Campomanesia cucullata is a tree from Monte Alegre, Pará, in the Brazilian Amazon. It is most similar to C. lineatifolia, from which it differs by being leafless when flowering, and by having densely congested and very small flowers. Myrcianthes monteucalyptoides is a tree from Tarma, Junín, in Central Peru. It is most similar to Myrcianthes myrsinoides, but the new species differs by a combination of medium-sized, somewhat revolute, broadly-acuminate leaves, and by the solitary, pentamerous flowers with delicate pedicels.     

Senecio josei and S. superparamensis spp. nov. (Asteraceae: Senecioneae) from the Andes of Ecuador

Research on the phylogeny of a distinct group of Andean Senecio, previously considered as Lasiocephalus, resulted in the discovery of two new species, which are here described and illustrated. Senecio josei Sklená?, which grows in rocky habitats in grass páramo in southern Ecuador, is characterized by linear leaves and a racemose or paniculate synflorescence. Senecio superparamensis Sklená? is characterized by grayish–white pubescence, solitary capitula and leafy stems, and inhabits superpáramos in northern and central Ecuador.     

THE COMPARATIVE MORPHOLOGY OF THE CANELLACEAE. IV. FLORAL MORPHOLOGY AND CONCLUSIONS

The morphology and anatomy of 105 flowers representing 13 species and 6 genera of the Canellaceae are summarized. The flowers are borne in axillary or terminal racemes, cymes, or small groups, or solitary, in an axillary or terminal position. The flowers are characterized as follows: bisexual, hypogynous; sepals 3, thick and leathery; petals, 5–12, free or united into tube at base, rather thick, in 1 or 2 whorls and/or spirals; androecium of 6–12 stamens united by their filaments forming a tube, anthers with longitudinal extrorse dehiscence; gynoecium of 2–6 carpels fused by their ventral margins; 2–6 placentae. There are 2 vascular bundles (rarely 3) to each sepal, 3 to each petal (some of the inner petals have only 1), 1 to each stamen and 1 trace to each carpel. The petal and stamen bundles have a common origin. All the data accumulated in this series on the Canellaceae indicate that the correct systematic placement of the Canellaceae is in the woody Ranales, perhaps in a complex with the Myristicaceae.     

MORPHOLOGICAL STUDIES OF THE NYMPHAEACEAE (SENSU LATO). XIII. CONTRIBUTIONS TO THE VEGETATIVE AND FLORAL STRUCTURE OF CABOMBA

Six species of Cabomba have been examined although the anatomy of the vegetative axes is based on the study of only C. caroliniana and C. palaeformis. A plant consists of an erect short shoot with decussate leaves which bears axillary flowering shoots and rhizomes. A rhizome bears decussate leaves and may also form axillary flowering shoots or turn upward and become a new short shoot. The phyllotaxies of the flowering shoots are proximately decussate or ternate (C. piauhyensis). The flowering shoots with decussate phyllotaxy change to 1/3 phyllotaxy distally; they bear axillary flowers proximally, and extra-axillary flowers distally. Flowering shoots with ternate phyllotaxy do not change distally but each produces first axillary and then extra-axillary flowers. Decussate vegetative axes and flowering shoots have four vascular bundles; ternate vegetative axes and flowering shoots have six vascular bundles, distantly paired into two or three vascular bundle-pairs, respectively. An elliptical vascular plexus occurs at each node. Each leaf receives one bundle-pair from one trace and each flower three bundle-pairs. A two-level receptacular vascular plexus occurs in flowers; the proximal, larger portion provides traces to perianth and stamens and the distal, smaller portion becomes carpellary traces. Each of the three sepals typically receives five branch traces from a basal principal trace, and each of the three petals receives, typically, three branch traces from a basal principal trace. Sepals and petals generally occur in a single, basally connate whorl. Each stamen receives one trace. Each stamen of three-stamen flowers is opposite a petal; each stamen of six-stamen flowers is aligned with an interval between a petal and adjacent sepal. Each staminal trace, which is just above the principal petal trace, in a three-petal flower, is frequently adnate to the latter trace. Each carpel receives one principal trace from the distal, small extension of the receptacular plexus, and each principal trace becomes three conventional veins of a carpel. Ovules may be borne directly over one of the veins or in any position between veins and are supplied by branches of the nearest vein or nearest two veins. All traces, ovular supply veins and the proximal portions of all veins are amphicribral. The several anatomical and morphological differences in vegetative axes and flowers between Cabomba and Brasenia suggest a greater taxonomic distance between the two genera than commonly supposed. It is suggested that extra-axillary flowers in 1/3 helical and ternate flowering shoots of Cabomba might be advantageous in preventing anthesis of flowers beneath peltate leaves. The aberrant position might be the initial evolutionary step toward what, in other nymphaeaceous genera, has shifted each flower to an adjacent helix. It is proposed that the zigzag stem accompanying the trigonal and sympodial flowering shoots may offer greater stability and floatability in water than the monopodial form. Several suggestions are offered for the variability of ovular positions: 1) the variability is a vestige of former laminar placentation in conduplicate carpels; 2) it is a vestige of a primitive condition antedating the current close association of ovules with ventral carpellary veins; 3) it is an early stage of evolution which might have terminated in laminar placentation and cantharophily, but which was replaced by a trend toward myophily.     

Synflorescences of species related to Schizachyrium condensatum (Poaceae)

The synflorescences of species related to Schizachyrium condensatum are typologically characterized. This species presents floriferous shoots with complex systems of ramification. In all species the inflorescence is polytelic and truncate. The typological pattern has been described and presents differences in the following parameters: length and shape of the synflorescence, paracladia of the trophotagma subzone and short paracladia subzone. A comparative analysis of the variations observed in the structure of the synflorescence is included.     

Sexual dimorphism and sex ratios of two Australian dioecious species of alpine pineapple grass, Astelia alpina var. novaehollandiae and Astelia psychrocharis (Asteliaceae)

Sexual dimorphism and male biased sex ratios have been predicted for dioecious plants experiencing the limited conditions for growth and reproduction found in many alpine environments. To test these predictions, the reproductive ecology of two congeneric, co-occurring, dioecious, clonal, species was examined in the subalpine and alpine zones of Kosciuszko National Park, southeastern Australia. Specifically, plant size (vegetative cover of plants in quadrats), floral display (number of flowers per inflorescence, number of inflorescences per quadrat) and sex ratios (proportion of females in quadrats with flowers) were examined in ten populations of Astelia psychrocharis (Asteliaceae) and nine populations of Astelia alpina var. novae-hollandiae (Asteliaceae). Sexual dimorphism did occur, with males having more flowers per inflorescence (106% more flowers for A.alpina males and 12% more for A.psychrocharis males compared to females) and more inflorescences per quadrat than females (78% more inflorescences for A.alpina males and 46% more inflorescences for A.psychrocharis males compared to females). Plant size did not differ between male and female quadrats of either species, nor were there male biased sex ratios. However, plant size was related to flowering status in A.psychrocharis with the 65 quadrats that did not flower having lower vegetative cover than the 175 flowering quadrats indicating that there may be a minimum size/ cover required prior to flowering in this species. For A.alpina, all but two of the 185 quadrats randomly sampled flowered. There was no effect of altitude on plant size and very little effect of altitude on floral display for either species, apart from a slight increase in the number of inflorescences per quadrat with increasing altitude for A.psychrocharis, and slight decrease in number of flowers per inflorescence with increasing altitude for A.alpina females.     

Phenological regulation of opportunities for within-inflorescence geitonogamy in the clonal species,iris versicolor (iridaceae)

Opportunities for selfing through geitonogamy are possible if more than one flower within the same clone, inflorescence, or floral unit is open at the same time. In a total of 200 inflorescences in two natural populations of Iris versicolor, flowers were observed and classified daily on the basis of anther dehiscence and stigma receptivity. Analysis of the flowering phenology demonstrated that (1) protandry limits opportunities for autogamy, (2) flowers mature sequentially within a floral unit (defined as a cluster of flowers borne on a single branch within an inflorescence), preventing the opportunity for geitonogamous fertilization between flowers of the same floral unit, and (3) 77% of all flowers had no opportunity to be pollinated by another flower within the same inflorescence. Both the number and the proportion of flowers with opportunities for geitonogamy increased with the number of flowers open in each population, and opportunities for geitonogamy also increased with the number of floral units within inflorescences. These morphological and phenological controls suggest that when selfing occurs in this species, it is most likely to occur between flowers on different inflorescences within the same clone. Since the organization of whole inflorescences in space is determined primarily by rhizome placement, clonal architecture may play an important role in mating system regulation in this species.     

Mechanisms that limit pollinator range in Ericaceae

Studies were conducted in 2001-2003 at Valdai National Park (Novgorod region) and at the Zvenigorod biological station of Moscow State University. The morphology of flowers, flowering dynamics and composition of insect visiting flowers of Ericaceae species: Andromeda polifolia, Chamaedaphne calyculata, Ledum palustre, Oxycoccus palustris, Vaccinium myrtillus, V. uliginosum, and V. vitis-idaea L. were studied. Some species of insects visiting flowers were excluded from the list of pollinators on the basis of observation on their behavior. L. palustre was visited mainly by flies where as other investigated species were visited mainly by bumblebees. In some cases bumblebees were the only visitors of the investigated plants. Mechanisms that protect flowers from flies and short-tongued solitary bees visits and ensure a best pollination by bumblebees are various among different species of Ericaceae. Efficiency of nectary protection also differs among different plant species and is defined by particularities of their habitats and flowering phenology. As far as all species of this family during the flowering are dominants in typical habitats, a competition for the pollination with species of other families in most cases is megligible. Flowering periods of V. vitis-idaea and V. myrtillus in forest ecosystems overlapped weakly. Moreover, V. myrtillus is pollinated mainly by bumblebee queens where as pollinators of V. vitis-idaea are bumblebee workers, solitary bees and horse flies. The other investigated plant species inhabit only oligotrophic peat bogs. Thery are pollinated by bumblebees but periods of flowering are not overlapped and consequently follow one after another. L. palustre and V. uliginosum flower simultaneosly but they are pollinated by different pollinators.     

Leaf size versus leaf numbertrade-offs in dioecious angiosperms

Aims We explore the possible role of leaf size/number trade-offs for the interpretation of leaf size dimorphism in dioecious plant species.Methods Total above-ground biomass (both male and female) for three herbaceous dioecious species and individual shoots (from both male and female plants) for three woody dioecious species were sampled to record individual leaf dry mass, number of leaves, dry mass of residual above-ground tissue (all remaining non-leaf biomass), number of flowers/inflorescences (for herbaceous species) and number of branches.Important findings For two out of three woody species and two out of three herbaceous species examined, male plants produced smaller leaves but with higher leafing intensity—i.e. more leaves per unit of supporting (residual) shoot tissue or plant body mass—compared with females. Male and female plants, however, did not differ in shoot or plant body mass or branching intensity. We interpret these results as possible evidence for a dimorphic leaf deployment strategy that promotes both male and female function, respectively. In male plants, capacity as a pollen donor may be favored by selection for a broadly spaced floral display, hence favoring relatively high leafing intensity because this provides more numerous axillary meristems that can be deployed for flowering, thus requiring a relatively small leaf as a trade-off. In one herbaceous species, higher leafing intensity in males was associated with greater flower production than in females. In contrast, in female plants, selection favors a relatively large leaf, we propose, because this promotes greater capacity for localized photosynthate production, thus supporting the locally high energetic cost of axillary fruit and seed development, which in turn requires a relatively low leafing intensity as a trade-off.