Flowers and inflorescences of the “Amentiferae”

The floral and inflorescence morphology of the major genera of the Myricaceae, Betulaceae (including Corylaceae), Fagaceae, Leitneriaceae, and Juglandaceae are reviewed. Major problems in interpretation of morphology are examined in the light of various comparative morphological studies as well as ontogenetic and vascular anatomical studies. Basically similar phenomena associated with miniaturization of the partial inflorescence have led to superficially similar morphological patterns. The partial inflorescences in the various families, in spite of their reduced size, can be adequately analyzed in most cases on the basis of the bract-branch relationship. The highly modified morphology of the floret is clarified by the application of the general tenets of the leaf-stem relationship in the frame of reference of the minute absolute size of the floret. Numerous problems remain to be attacked. The total and partial inflorescences and the florets of the Myricaceae, Betulaceae, Fagaceae, Leitneriaceae and Juglandaceae are reviewed in terms of external morphology, vascular anatomy and ontogeny as reported in the more objective literature on the subject. The total inflorescences in these families range from the complex, androgynous panicles of stiff spikes of such genera asCastanopsis to the condensed, bud-like pistillate spikes of some Myricaceae andCorylus on the one hand, to the simple staminate floret in the axil of the foliage leaf in some species ofNothofagus on the other. In many species of these families the inflorescence is the apparently simple spike with a flaccid axis, the ament, but so often is this not the case that the designation “Amentiferae” for this artificial assemblage must be considered a misnomer. Whether the total inflorescences are composed of racemose or cymose partial inflorescences is a question not completely answered in all the families. In the Betulaceae the partial inflorescence has long been taken to be a cymule. But, a re-interpretation of the vascular anatomy suggests the alternative that the most distal floret in a short raceme has overtopped the axis of the partial inflorescence thus producing a pseudo-cymule. This is similar to a recent interpretation of the staminate partial inflorescence ofMyrica esculenta, where the individual floret is composed of a single stamen. The partial inflorescence in the more reduced species ofMyrica is thus a pseudanthium. Recent ontogenetic studies in the Betulaceae dramatically corroborate the earlier interpretation, based on vascular anatomy, that the staminate partial inflorescence ofOstrya is three-flowered. On similar grounds it has recently been shown that the spiny “involucre” of pistillateComptonia is composed of tertiary bracts. The structure of the staminate partial inflorescences in the Fagaceae seems reasonably clear except in certain species ofNothofagus where it may well be a synanthium, although the alternative of chorisis exists. The interpretation of the pistillate partial inflorescence inLeitneria requires re-study; the unvascularized tepal-like structures subtending the ovary have been alternatively treated as bracts -an ontogenetic study is badly needed. The organization of the staminate partial inflorescence of the Juglandaceae remains equivocal, although recent ontogenetic work on one species ofJuglans shows that the primordia of the secondary bracts are readily distinguished from tepal primordia, although at anthesis they are very similar. At present the number of florets in the partial inflorescence of the Juglandaceae remains an open question in spite of a fragmentary study of the vascular system. The cupule ofLithocarpus andQuercus continues to present a major morphological problem. The valves of the husk in other genera of the Fagaceae seem, on the basis of the vascular anatomy and some ontogenetic information, to be axes of the ultimate order of branching. A thorough study of these complex structures is needed. Staminate florets which are set off by tepals are readily identified with the reservation that those of some species ofNothofagus and ofJuglans, for instance, may be more complex than they seem. The absence of tepals creates major difficulties which have been resolved in some instances by the study of the vascular anatomy and/or ontogeny. But many problems remain. The pistillate floret seems clearly delimited in the various families. There continues to be the usual conflict concerning the proper interpretation of the wall of the inferior ovary, whether on the basis of ontogeny it should be considered cauline or on the basis of the vascular anatomy it is to be considered appendicular. Oddly enough there are also diametrically opposed interpretations of placentation -is it axile or parietal in one and the same species. This perhaps results from a conceptual conflict. The basal ovule, as in the Myricaceae, or even the ovules perched on a partial septum, as in the Juglandaceae, are similarly much discussed. The ontogenists tend to agree that such ovules are cauline, while the anatomists find that the complex vascular system is not that of a stele. There is a multitude of discrepancies, as yet, in observations, and even when there is mutually accepted fact, there are often conflicting interpretations. Above all, there is a massive lack of knowledge of the vascular anatomy and ontogeny of these miniature and modified flowers and inflorescences.     

Hybridization in the babassu palm complex. II. Attalea compta × Orbignya oleifera (Palmae)

A new hybrid palm, ×Attabignya minarum, from the Rio São Francisco Valley of Minas Gerais, Brazil is described. It is a natural hybrid betweenAttalea compta Mart. andOrbignya oleifera Burret and is quite common in the area studied. Most of the morphological characters of the hybrid are intermediate between those of the parent species. A notable exception is the number of fruits produced; ×Attabignya minarum produces more fruits per panicle than either parent species. This is the first report of hybridization betweenOrbignya andAttalea and may shed light on the status ofOrbignya, considered by some to be synonymous withAttalea.     

Making and marketing Chambira hammocks and bags in the village of Brillo Nuevo, Northeastern Peru

Astrocaryum chambira Burret is a palm that provides edible fruits and fibers for making handicrafts. This study focused on the fiber products (hammocks and bags) made by the Bora in the Peruvian Amazonia. Making chambira handicrafts consists of several different phases. Handicrafts are marketed to tourists, river traders, or shopkeepers in the city of Iquitos. Villagers travel actively to sell their products because of the remote location of the village from the market. The prices received by producers were extremely low when considering the amount of work, but the prices were low also in other steps (middleman, tourist). Still, chambira works provide an important source of income for villagers. The greater abundance ofA. chambira in secondary forest compared with the primary forest indicates that it has potential for agroforestry. Agroforestry systems can provide a sustainable way to use land in the rainforest areas in NE Peru, and in this system nontimber forest products may have an important role.     

The Physiological Response of Two Green Calcifying Algae from the Great Barrier Reef towards High Dissolved Inorganic and Organic Carbon (DIC and DOC) Availability

Increasing dissolved inorganic carbon (DIC) concentrations associated with ocean acidification can affect marine calcifiers, but local factors, such as high dissolved organic carbon (DOC) concentrations through sewage and algal blooms, may interact with this global factor. For calcifying green algae of the genus Halimeda, a key tropical carbonate producer that often occurs in coral reefs, no studies on these interactions have been reported. These data are however urgently needed to understand future carbonate production. Thus, we investigated the independent and combined effects of DIC (pCO₂ 402 μatm/ pH_tot 8.0 and 996 μatm/ pH_tot 7.7) and DOC (added as glucose in 0 and 294 μmol L^-1) on growth, calcification and photosynthesis of H. macroloba and H. opuntia from the Great Barrier Reef in an incubation experiment over 16 days. High DIC concentrations significantly reduced dark calcification of H. opuntia by 130 % and led to net dissolution, but did not affect H. macroloba. High DOC concentrations significantly reduced daily oxygen production of H. opuntia and H. macroloba by 78 % and 43 %, respectively, and significantly reduced dark calcification of H. opuntia by 70%. Combined high DIC and DOC did not show any interactive effects for both algae, but revealed additive effects for H. opuntia where the combination of both factors reduced dark calcification by 162 % compared to controls. Such species-specific differences in treatment responses indicate H. opuntia is more susceptible to a combination of high DIC and DOC than H. macroloba. From an ecological perspective, results further suggest a reduction of primary production for Halimeda-dominated benthic reef communities under high DOC concentrations and additional decreases of carbonate accretion under elevated DIC concentrations, where H. opuntia dominates the benthic community. This may reduce biogenic carbonate sedimentation rates and hence the buffering capacity against further ocean acidification.     

Morphological studies on the genusClematis Linn

While the axes of branched axillary inflorescences seen in most species ofClematis show fundamentally the same features in nodal vasculature as the vegetative stems, those of simple axillary inflorescences, having only a pair of opposite sterile bracts at specific positions, exhibit an exclusive feature in nodal vasculature because they have entirely lost lateral branches or buds in the bract axils. Noticeably, at the nodal level of the axis of the simple inflorescence ofC. japonica andC. Williamsii, trace bundles to the missing lateral branches are formed and extend unaltered beyond the node. Thus, in these two species stelar bundles in the inflorescence axis generally increase in number upwardly from six to eight or more through the node with sterile bracts. On the basis of both anatomical and morphological data, a probable evolutionary trend in floral shoots with simple axillary inflorescences is proposed. The type of floral shoot ofC. tosaensis bearing simple, scale-subtended and basally fascicled inflorescences is the most primitive and constitutes an initial phase of evolution, and progressive changes in a kind of inflorescence-subtending leaves as well as in the shape and position of the sterile bracts resulting in the type of floral shoot ofC. japonica and further in that ofC. obvallata. A floral shoot ofC. Williamsii follows another line of evolution from an ancestral type similar to that ofC. tosaensis.     

Ethnobotany of the fiber palmAstrocaryum chambira (Arecaceae) in Amazonian Ecuador

Astrocaryum chambira Burret is native to the western parts of the Amazon basin where indigenous people use it as a source of fiber. Its use among four different indigenous groups in Ecuador is described here. They extract fibers from the pinnae, mostly of the young leaves. Both men and women twist the fibers into strings in their homes after hunting and work in the fields. The main items produced are woven hammocks, bags, and nets. These products represent the main source of cash income for many indigenous people. The highest value for their products is obtained from sale directly to tourists. The commercial use ofA. chambira can possibly be increased in extractivism along with better marketing. The variety of ways this palm is used also makes it a valuable species for agroforestry.     

Aiphanes tricuspidata (Palmae), a new species from Colombia and Ecuador

Aiphanes tricuspidata, a new species from Colombia and Ecuador is described and illustrated. It differs from the most similar species,A. deltoidea Burret, in its solitary habit the tricuspidate pinnae, and a completely different flower arrangement.     

The branching of the inflorescence and vegetative shoot and taxonomy of the genusKummerowia (Leguminosae)

A study of the branching of the inflorescence and the vegetative shoot of the genusKummerowia, consisting ofK. stipulacea (Maxim.) Makino andK. striata (Thunb.) Schindler, has led to the following conclusions: (1) the inflorescences of both species are reduced compound cymes, (2) the branching system of the inflorescence ofKummerowia is not clearly different from that of the vegetative shoot and there are some transitional forms between both systems, and (3) the inflorescence ofKummerowia is different from the racemose inflorescences ofLespedeza andCampylotropis. Based on the differences found in the branching system of the inflorescence,Kummerowia is distinctly separated fromLespedeza andCampylotropis and is more correctly treated as a distinct genus from the latter two.     

Grias longirachis (Lecythidaceae), a new species from northwestern Ecuador

A new species,Grias longirachis S. A. Mori & J. L. Clark, with enclosed calyx in bud and unusually long inflorescence rachises, is described based on collections from northwestern Ecuador. A key to the species ofGrias is provided.     

Studies in eupatorium (Compositae), III. Apparent wind pollination

Eupatorium is a large, chiefly American genus in which some species have deviated from the usual reproductive methods of insect pollination and outcrossing. Apomixis and autogamy are two reproductive specializations which have been reported previously. A third, anemophily, is suspected inE. solidaginifolium, E. solidaginoides, E. monanthum, and several other species. Our assumptions are based upon morphological modifications of the inflorescence, anther appendages, style branches, and pollen. Wind pollination in the Compositae has heretofore been known only in the tribe Anthemideae and the subtribe Ambrosinae of the Heliantheae; its occurrence inEupatorium is an independent evolutionary event. The occurrence of apomixis, autogamy, and anemophily in members ofEupatorium from the same geographical region probably represents (at least in part) correlated responses to the same environmental stress, a scarcity of insect pollinators.     

High morpho‐anatomical variability in Halimeda macroloba (Bryopsidales,Chlorophyta) in Thai waters

Halimeda macroloba is a common widespread and morphologically variable species in the Indo‐Pacific Ocean. A series of morphometric data (16 morphological and 46 anatomical variables) and the chloroplast‐encoded tuf A gene were examined to explore the morphological and genetic variations within the species and to better determine species boundaries in H. macroloba in Thai waters. Moreover, the environmental conditions, which may affect morphological variations in H. macroloba, especially of Haplotype I were examined. Our results showed that H. macroloba has more morpho‐anatomical variability and broader species boundaries than previously thought in several characters: holdfast type, segment shape and size, node height with differences in pore size, the presence of two additional patterns of peripheral utricle as seen in surface view, and additional layers of utricles (up to seven layers). Additionally, two new variable characteristics have been reported for the first time, i.e. shape and margin of peripheral utricles. Water depth and light correlated with thallus morphology, larger thalli and segments with a greater number of utricle layers were associated with subtidal plants, while smaller thalli and segments were found in the intertidal or high light intensity areas. The high plasticity of this species may explain why in the Indo‐Pacific Ocean this species is common and dominant.     

Species- and site-specific bacterial communities associated with four encrusting bryozoans from the North Sea, Germany

Epi- and endozoic bacterial communities associated with four bryozoan species from the Jade (North Sea, Germany) were investigated by the combined application of molecular tools and electron microscopic visualisation of zooids. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments of associated bacteria displayed specific bacterial community profiles in the examined species Aspidelectra melolontha, Conopeum reticulum, Electra monostachys and Electra pilosa. Actual bacterial epibiosis was only observed on C. reticulum whilst the other bryozoans under investigation were largely free of microbial epibionts. These observations indicated that bryozoan-associated bacteria identified by molecular methods originated from internal cavities of bryozoan zooids. Cluster analysis of DGGE band patterns revealed species-specific bacterial communities in A. melolontha, E. monostachys and E. pilosa. Bacteria associated with C. reticulum were seemingly influenced by site-specific parameters. A comparison of bacterial community profiles between reference and invertebrate surfaces allowed for an interpretation of conspicuous group-specific differences. Operational taxonomic units (OTUs) obtained from a single set of bryozoan replicates that were absent on the inorganic reference samples (mussel shells) were hypothesized to be favourable endobionts. Contrary, OTUs present in the references but absent in bryozoan samples could be assumed to stem from bryozoan-specific defenses against ubiquitous bacterial colonizers. Although there was no experimental evidence for a mutual relationship between prokaryotes and their eukaryotic bryozoan hosts, this study demonstrated that in three out of four bryozoans under investigation associated bacterial communities were characteristically shaped by host attributes.     

Asphodelus aestivus,an example of synchronization with the climate periodicity

The phenology ofAsphodelus aestivus Brot. is described by means of a phenological model which has been formulated to fit skewed phenological data. Based on the model parameters the timing of different phenophases of biomass accumulation were determined. The biomass oscillations of leaves, inflorescence stalks and tubers were found to be synchronized with the predictable seasonal climatic changes. In addition, the plant seems to respond to minor random climatic variations. The emergence of leaves and inflorescence stalks depends on stored material in the tubers while leaf and inflorescence stalk elongation as well as flowering depends on current production. The storage part of the tubers seems to be a regulating structure, which is responsible for the synchronization ofA. aestivus productivity with the seasonality of the Mediterranean climate.A. aestivus is considered to be a Competitor Ruderal and Stress tolerant (C-R-S) strategist which may explain the wide distribution of this plant over the Mediterranean Basin.     

Reinstatement of the genus Hymenaea (Leguminosae: Caesalpinioideae) in Africa

The monotypic genusTrachylobium [T. verrucosum (Gaertn.) Oliv.] from East Africa and adjacent islands is returned toHymenaea verrucosa Gaertn. on the basis of reevaluation of inflorescence, flower, and fruit characters together with new evidence from seedlings, pollen, leaf venation, chromosome number, and chemistry of the resins.Hymenaea verrucosa appears more similar to an Amazonian and Cuban group of species, which may have been derived from a common African ancestral stock in the Tertiary period, than to another group of species that probably evolved from the evergreen forest species and then radiated into an expanding area of drier habitats during the later Tertiary and dry intervals of the Pleistocene. Originally the genusTrachylobium was distinguished fromHymenaea by a morphological comparison with the probably more recently evolved species. A possible explanation is presented for the disjunct amphi-Atlantic distribution ofH. verrucosa and the neotropical species ofHymenaea.     

The taxonomic status of clematis gattingeri small (Ranunculaceae)

Recognition ofClematis gattingeri Small as an independent species has been based primarily on the smaller flowers and glandular pubescence of specimens collected from 1897 to 1901 by A. Gattinger. Recent studies have indicated that flower size varies among all members of subsect.Viornae to whichC. gattingeri belongs and should not be considered a significant taxonomic character for species delimitation. Studies using both light and scanning electron microscopy confirm the presence of glandular pubescence on Gattinger’s specimens, but other specimens with glandular pubescence have never since been found.Clematis gattingeri is believed to have been a minor variant ofC. viorna L. and is accordingly placed in synonymy.     

Papilionoid inflorescences revisited (Leguminosae-Papilionoideae)

Background and Aims

The inflorescence structure determines the spatiotemporal arrangement of the flowers during anthesis and is therefore vital for reproductive success. The Leguminosae are among the largest angiosperm plant families and they include some important crop plants. In papilionoid legumes, the raceme is the most common type of inflorescence. However, a range of other inflorescence types have evolved via various developmental processes. A (re-)investigation of inflorescences in Swainsona formosa, Cicer arietinum, Abrus precatorius, Hardenbergia violacea and Kennedia nigricans leads to new insights into reduction mechanisms and to a new hypothesis on the evolution of the papilionoid pseudoraceme.

Methods

Inflorescence morphology and ontogeny were studied using scanning electron microscopy (SEM).

Key Results

The inflorescence in S. formosa is an umbel with a rare type of pendulum symmetry which may be triggered by the subtending leaf. Inflorescences in C. arietinum are reduced to a single flower. An early formed adaxial bulge is the sterile apex of the inflorescence (i.e. the inflorescence is open and not terminated by a flower). In partial inflorescences of A. precatorius, the axis is reduced and its meristem is relocated towards the main inflorescence. Flower initiation follows a peculiar pendulum pattern. Partial inflorescences in H. violacea and in K. nigricans show reduction tendencies. In both taxa, initiated but early reduced bracteoles are present.

Conclusions

Pendulum symmetry in S. formosa is probably associated with distichous phyllotaxis. In C. arietinum, strong reduction tendencies are revealed. Based on studies of A. precatorius, the papilionoid pseudoraceme is reinterpreted as a compound raceme with condensed lateral axes. From an Abrus-like inflorescence, other types can be derived via reduction of flower number and synchronization of flower development. A plea is made for uniform usage of inflorescence terminology.Key words: Abrus precatorius, Cicer arietinum, Hardenbergia violacea, Kennedia nigricans, inflorescence, Leguminosae, Papilionoideae, pseudoraceme, Swainsona formosa     

Assimilation of 14CO2 by the Inflorescence of Poa annua L. and Lolium perenne L.

The relative assimilatory activity of the inflorescence, itsindividual components, and the leaves of flowering tillers ofPoa annua L. and Lolium perenneL. was determined over the periodfrom inflorescence emergence to seed shedding. The pattern of¹⁴CO₂ fixation was similar for both species and the inflorescencewas by far the most important assimilatory organ of the reproductivetiller, particularly over the latter period of seed developmentas leaf senescence progressed. With the exception of the seedsall parts of the inflorescence showed significant assimilatoryactivity and the lemmas and paleas accounted for 40–50per cent of the total ¹⁴C fixed by the inflorescence in bothspecies. The importance of the grass inflorescence as a photosyntheticstructure is discussed in relation to similar studies on cereals. Poa annua, Lolium perenne, carbon dioxide assimilation, inflorescence     

Chemical defense and chemical variation in some tropical Pacific species of Halimeda (Halimedaceae; Chlorophyta)

Over a dozen species of the genus Halimeda have been chemically investigated and found to produce the diterpenoid metabolites halimedatrial (1) and halimedatetraacetate (2) in varying concentrations. These meabolites have been proposed to play a role in chemical defense against herbivores based on their chemical structures and their demonstrated biological activities in laboratory and aquarium assays. We examined and compared the feeding deterrent effects of these two compounds tovard herbivorous fishes in field experiments on Guam reefs. Halimedatrial is a more effective feeding deterrent than halimedatetraacetate. It is the major secondary metabolite in young Halimeda macroloba and in the newly produced segments of growing plants. The organic extracts from young plants and new segments were significantly more deterrent than extracts from mature plant tissue. Some populations of Halimeda growing in reef-slope habitats, where herbivory is intense, also have high concentrations of halimedatrial. We compared extracts between reef slope and reef flat collections of Halimeda opuntia on Guam and Pohnpei (= Ponape), and H. discoidea and H. macroloba on Guam. We found that halimedtrial was the major metabolite in reef-slope collections of H. opuntia from Pohnpei and Pago Bay, Guam, and that halimedatetraacetate was the major metabolite a non-reef slope populations. In the cases examined, chemical defenses were greatest in (1) plant parts and (2) populations that were at greatest risk to herbivores.     

CENTRORADIALIS/TERMINAL FLOWER 1 gene homolog is conserved inN. tabacum, a determinate inflorescence plant

A mutation in theCENTRORADIALIS (CEN) gene ofAntirrhinum and in theTERMINAL FLOWER 1 (TFL1) gene ofArabidopsis causes their indeterminate inflorescence to determinate. We clonedCEN/TFL1 homologs fromNicotiana tabacum, the wild-type of which has a determinate inflorescence. TheCEN gene was expressed in the inflorescnece meristem and kept its inflorescence meristem identity, whereas the tobacco homolog (NCH) was expressed at a low level throughout the plant’s development. AlthoughCEN andNCH are highly homologous genes, they may have been recruited to different developmental functions during their evolution. TwoNCH genes are derived from amphidiploidN. tabacum, but both of them hybridized with its diploid parents,N. sylvestris andN. tomentosiformis. Southern blotting, and the genomic organization ofTFL1 inArabidopsis revealed that anotherCEN homolog exists in the genome ofArabidopsis. These results suggest that there are two copies of theCEN homolog per diploid plant. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology” These two authors contributed to this work equally.     

Sesquiterpenes of six Porella species (hepaticae)

The distribution in six Porella species of drimane-, aromadendrane- and pinguisane-type sesquiterpenes and norsesquiterpenes is described. The sharp pungent substance of P. gracillissima, P. fauriei and P. macroloba is (+)-tadeonal.