Axils Of Bracts Research Articles

Vegetative and reproductive morphology of Othniophyton elongatum (MacGinitie) gen. et comb. nov., an extinct angiosperm of possible caryophyllalean affinity from the Eocene of Colorado and Utah, USA.

Eocene foliage formerly attributed to the extant araliaceous genus Oreopanax was found attached to twigs bearing inflorescences and infructescences unlike those of Araliaceae. Using newly observable characters of phyllotaxy, vegetative and floral buds, infructescences and seeds, we sought to reassess the affinities of this strange angiosperm. Fossils were studied from the Parachute Creek Member of the Green River Formation from near Bonanza, Utah and Douglas Pass, Colorado (ca. 47 Ma). Macrofossil impression remains were investigated by low angle reflected light and subtle details of the vegetative and floral buds, stamens, mature fruits, and seeds were revealed by optical shadow effect microscopy documenting previously obscure topographic surface features. Othniophyton elongatum (MacGinitie) Manchester, Judd, Correa-Narvaez gen. et comb. nov. has simple, short-petiolate, elongate, entire-margined leaves with thick midveins, pinnate, brochidodromous secondaries, common intersecondary veins and finely reticulate higher order venation. Inflorescences are small axillary cymes; flower buds are subglobose and pedicellate, in bract axils. The flowers are actinomorphic, bisexual, with ca. five imbricate perianth parts, ca. 24 stamens with elongate anthers and short filaments, arising from a hypanthium. The whorl of stamens persists to fruiting stage. The ovary is superior, with probable basal placentation and five stigmatic arms. Fruits are pedicellate berries with a cup-shaped hypanthium and contain ca. 15 lensoidal reniform seeds, each with a curved embryo and ornamented with concentric ridges. The combined characters refute the prior placement in Araliaceae, and rule out affinities with most extant clades of angiosperms. The distinctive combination of observed features does not coincide with any extant family. Among extant orders of Eudicots, the fossil seems to conform most closely to the order Caryophyllales, but key differences remain. This example indicates that the vegetation of ca. 47 million years ago included some taxa that cannot readily be placed in modern families and genera.

Tinnea gombea (Lamiaceae), a new species from the Sudanian savanna region, Nigeria based on integrative evidence.

Tinnea gombea, endemic to the Sudan savanna grasslands in northern Nigeria, is described and illustrated. We used integrative evidence from morphological characters, ecology and molecular phylogenetic data. The new species is morphologically and ecologically similar to T. barteri and T. aethiopica, but can be readily delimited from these taxa by unique characters including a subshrub growth habit, leaves alternate to subopposite, blades lanceolate, apically acuminate, inflorescences raceme, bearing solitary flowers in upper leaf and bract axils, lilac to purplish dusky flowers and the inflated fruits dehiscent. The distribution and habitat of T. gombea are also distinctive, being restricted to the Sudan savanna, while the two most similar species are widespread in tropical Africa. Additionally, molecular phylogenetic assessments using nrITS and chloroplast trnL-F, matK and rbcL support the placement of T. gombea as a distinct species. Tinnea gombea is here assessed as Critically Endangered due to its small population size and restriction to a small area lacking conservation prioritization.

<strong>From the frying pan: an unusual dwarf shrub from Namibia turns out to be a new brassicalean family</strong>

Tiganophyton karasense, an evergreen dwarf shrub, is described as a new species. A new genus and family are also proposed for it in the order Brassicales. Phylogenetic analysis of DNA sequence data indicate that Tiganophyton is sister to Bataceae/Salvadoraceae, and all three sister to Koeberliniaceae. First realized to be undescribed in 2010, T. karasense is a rare species known only from three localities in the arid Karas Region, southern Namibia. These small shrubs grow near the edges of seasonal pans on calcareous substrate underlaid by shales and mudstones of the Prince Albert Formation of the Karoo Supergroup. Morphological characters diagnostic of the new family include: a marked differentiation into long and short shoots; dimorphic, spirally arranged leaves; glucosinolate production; bisexual laterally flattened flowers borne singly in bract axils on short shoots only; tetramerous calyx, corolla and androecium with fused sepals and free, non-clawed petals; a staminal disc, but no nectary glands; deeply bilobed ovary with a gynobasic style; S-shaped gynophore supporting a bilocular, horizontally orientated or inverted ovary; two ovules per locule; and a dry, persistent fruit, provisionally interpreted as a one-seeded nutlet. Based on IUCN Red List categories and criteria, a conservation assessment of Vulnerable (VU D1) is recommended for Tiganophyton karasense.

A taxonomic revision of Thesium section Hagnothesium (Santalaceae) and description of a new species, T. quartzicolum

Thesium L., section Hagnothesium is endemic to the Greater Cape Floristic Region (GCFR), South Africa. In the past there has been a propensity in revisionary work of the section Hagnothesium to split taxa into distinct species or vice-versa. Consequently, 15 different names exist although only 6 are accepted formally. Following recent molecular phylogenetic studies, the monophyly of the section Hagnothesium is now well-established but the circumscription of species within the section remains problematic given the complicated nomenclatural history which has added further confusion. In this paper we revise the section using a total evidence approach to propose a revised taxonomy. We studied both herbarium collections as well as plants in their natural populations to circumscribe species boundaries, determine their geographical ranges and estimate their conservation statuses. Species of the section Hagnothesium are dioecious, generally having four-merous campanulate flowers produced in spikes borne in bract axils and arranged along the length of branchlets, with valvate perianth lobes and a short to absent hypanthial tube. We recognise eight species, of which one is described in this study as new: T. fragile L.f., T. fruticulosum (A.W.Hill) J.C.Manning & F.Forest, T. hirtum (Sond.) Zhigila, Verboom & Muasya comb. nov., T. leptostachyum A.DC., T. longicaule Zhigila, Verboom & Muasya nom. nov. T. microcarpum A.DC., T. minus (A.W.Hill) J.C.Manning & F.Forest) and T. quartzicolum Zhigila, Verboom & Muasya sp. nov. We provide updated taxonomic keys, species descriptions, illustrations, distribution maps, new combinations, synonyms, and notes on the red list status for each species.

Towards a Revision of Diastema within Central America

Diastema is a genus of flowering plants within the subtribe Gloxiniinae (Gesneriaceae). Some key characteristics of Diastemainclude a racemose flowering axis consisting of solitary flowers in the axils of bracts on the stems with condensed internodes, nectary consisting of 5 finger-like glands, and a distinctive bi-lobed stigma. Interestingly, there are currently only twenty described species and Diastemahas not been the focus of adequate research until now. I have collected a sufficient sample size of morphological and molecular data from both known and unknown species. Any new potential new species are compared to the appropriate type specimens to determine circumscription. Moreover, morphological studies focus on taxonomically useful vegetative and reproductive characters with special emphasis given to trichome structure and fruit shape. Molecular studies are focused on nuclear and chloroplast genes to ascertain if any hybridization has occured. Several samples of DNA are now ready to be sequenced for a more comprehensive understanding of the genus. The outcomes of this research will provide a baseline for conservation and governmental agencies to work from to protect the habitat where these species exist and to better understand the biodiversity in their area. My research is used toward a more comprehensive study of the subtribe and genus.

Towards a Revision of Diastema within Central America

Diastema is a genus of flowering plants within the subtribe Gloxiniinae (Gesneriaceae). Some of the key characteristics of Diastema are a racemose flowering axis consisting of solitary flowers in the axils of bracts on the stems with condensed internodes, nectary consisting of 5 finger-like glands, and a distinctive bi-lobed stigma. There are currently only twenty described species and there has been very little research performed on the genus. I am currently collecting morphological and molecular data to delineate species. Any new potential new species are then compared to the appropriate type specimens to determine circumscription. Morphological studies focus on taxonomically useful vegetative and reproductive characters with special emphasis given to trichome structure and fruit shape. Molecular studies are focused on nuclear and chloroplast genes to ascertain if any hybridization has occured. The outcomes of this research will provide a baseline for conservation and governmental agencies to work from to protect the habitat where these species exist. My research will be used toward a more comprehensive study of the subtribe and genus.

Towards a revision of the genus Diastema within Panama

Diastema is a genus of plants within the subtribe Gloxiniinae (Gesneriaceae). Some of the key characteristics of Diastema are a racemose flowering axis consisting of solitary flowers in the axils of bracts on the stems with condensed internodes, nectary consisting of 5 finger-like glands, and a distinctive bi-lobed stigma. I am currently collecting morphological and molecular data and will complete field studies of the genus Diastema. Morphological studies will focus on taxonomically useful vegetative and reproductive characters with special emphasis given to trichome structure and fruit shape. Field work will be carried out in northern Panama. I will be observing the ecology and population structure of the local species. Field studies will provide an opportunity to obtain data that is not easily observed on herbarium specimens. The outcomes of this research will provide a baseline for conservation and governmental agencies to work from to protect the habitat where these species exist. Evolutionary studies will be completed following the field study to ascertain the relationships between the species present. My research will be used toward a more comprehensive study of the subtribe and genus.

Patterns and Polarity in Floral Meristem and Floral Organ Initiation

The initial event in plant floral organogenesis is bract specification, followed by floral meristem (FM) initiation in bract axils, but initiation signals and the interplay between both lateral organs remain unelucidated. Floral organs are initiated on the flanks of the outgrowing FM and the enormous diversity in floral morphology throughout the plant kingdom reflects variations in organ position, meristy and ontogeny. Classical models of floral development have focused on Arabidopsis, which has mostly actinomorphic flowers, and Antirrhinum, which exhibits zygomorphy, although neither species is typical or representative of angiosperm flower diversity. Although the ABCE model defines a centripetal model of organ identity establishment in different whorls, the characterization of floral organ initiation in many species has relied on their morphological appearance, due to a lack of founder cell-specific markers. Recent progress in early Arabidopsis floral development using histology, molecular markers and mutants has led to refinements of existing floral organ initiation paradigms. In Arabidopsis, sepals initiate unidirectionally, in a temporal window characterized by the absence of CLAVATA3 and WUSCHEL stem cell markers and are partly dependent on PRESSED FLOWER function, whereas initiation of inner-whorl organs occurs centripetally. Arabidopsis mutants reveal that the FM is highly polarized along an ab-/adaxial axis and a comparison of floral development in Arabidopsis and Antirrhinum suggests that heterochrony of conserved gene functions has been evolutionarily adaptive.This review discusses current views on FM and organ specification signals, the gene regulatory networks that underlie floral meristem polarity, and analogies between the development of floral and leaf primordia as lateral organs. Alternative stem-cell proliferation mechanisms and the bifurcation of founder cell populations can help to explain the diversity in floral diversity throughout the plant kingdom and underpin comparative evolutionary biology and macroevolution. An analysis of plants with divergent body plans at the level of organ specification is urgently needed.

Epigenetic variation of the choriflowered-symflowered character in the symflowered sugar beet line SOAN-14

The effect of 5-azacytidine on the variation of the choriflowered (CF)-symflowered (SF) character in sugar beet was studied in several generations obtained via seed reproduction. The epimutagen (5-azacytidine) significantly reduced the number of flowers in glomerate inflorescences in the year of seed treatment and in the next generation (Az1), leading to the appearance of plants with single flowers in bract axils of a flower stalk. The CF character resulting from epimutagene treatment of sugar beet seeds (plants with genotype M(Z)M(Z) was inherited as a monohybrid character in both zygotic and apozygotic seed progenies. The proportion of the CF and SF phenotypes in the progenies was affected bythe chromatid number in the chromosomes (mixoploidy of the cell populations). Alleles of the Mm locus were found to affect the variation in phytomere organization of flower stalks.

Comparison of Early Inflorescence Development between Japanese Pear (Pyrus pyrifolia Nakai) and Quince (Cydonia oblonga Mill.)

Japanese pear (Pyrus pyrifolia) and quince (Cydonia oblonga) form different inflorescence architectures, the former forms raceme inflorescence with about eight flowers and the latter forms solitary-flowered inflorescence. We observed the floral differentiation of Japanese pear and quince to clarify the differences in their early inflorescence development. Floral differentiation of Japanese pear occurred in late June. After apical meristem turned to a dome-like structure, inflorescence developed by forming lateral flower meristems in axils of bracts. The apex of inflorescence became the terminal flower meristem, two or three meristems were initiated in axils of outer bracts and leaf primordia, and finally approximately eight flower meristems were formed in the inflorescence. Floral differentiation of quince was initiated from late October to November after eight leaf primordia had been initiated. Apical meristem transformed to a dome-like structure and initiated sepal primordia. Axillary meristems of bracts or leaf primordia in Japanese pear differentiate to flower meristem while those in quince remained undifferentiated to form axillary buds in the following growing season, resulting in an inflorescence architecture difference in Japanese pear and quince.

Discovery of organic connection ofChiropteris Kurr andNystroemia Halle from Early Permian of western Henan, China

Nystroemia reniformis (Kawasaki) comb. nov. is proposed based on specimens showing organic connections betweenChiropteris reniformis Kawasaki andNystroemia pectiniformis Halle from the Lower Permian of Dengfeng in Henan. Vegetative leaf has a long petiole, reniformed, cordate at the base, entire or slightly undulate at the margin; veins are fine, bifurcating repeatedly and finally becoming reticulate and forming polygonal or rhomboidal meshes. Fertile shoot arises from bract axils. The form of the bract is identical to that of a vegetative leaf. Ovuliferous organ arises from the axil of leafy organ, or in other case, both ovuliferous and leafy organs irregularly arise from the axis of the fertile shoot respectively. Numerous bicornute platyspermic seeds are arranged in two rows, obconical, with micropyle pointing upwards. It may represent a new extinct gymnosperms.

Structure and developmental regulation of CONSTANS- LIKE genes isolated from Populus deltoides

Two CONSTANS- LIKE ( COL) genes, PdCO1 and PdCO2, were isolated from eastern cottonwood ( Populus deltoides Bartr. ex. Marsh. var. deltoides). PdCO1 is unique among all the characterized CONSTANS-LIKE genes in the plant kingdom in that the deduced protein sequence contains a putative signal peptide with a potential transmembrane helix at the N-terminal end. Current bioinformatics tools suggest that PdCO1 protein may be secreted. Immuno-blot analysis indicated that although the PdCO1 was abundant in leaf, it was not detected in the subtended bud. Temporal mRNA and protein expression of PdCO1 and PdCO2 was determined in the leaf and bud at the ninth node of shoots, where transition from vegetative to floral phase has been observed to occur. The expression of both genes in the leaf increased dramatically from March 30 to April 21 and decreased on May 9. The increased expression coincided with morphological changes occurring in the axillary meristem of the subtended bud and with increased abundance of PdCO1 protein in the leaf. These changes sequentially included (1) the cessation of leaf-primordium formation, (2) the transition of the axillary shoot apical meristem to an inflorescence meristem, (3) and the subsequent formation of bracts and floral meristems in the axils of bracts flanking the inflorescence meristem. The temporal expression of PdCO1 and PdCO2 prior to flower bud development suggests that these genes might be involved in floral induction.

Thucydiaceae Fam. Nov., with a Review and Reevaluation of Paleozoic Walchian Conifers

Abundant fossils of a single conifer species occur in a Pennsylvanian‐age deposit of eastern North America, providing the opportunity to describe a biological taxon of primitive conifers as well as to clarify the uncertain taxonomy and systematics of walchian conifers. Thucydia mahoningensis gen. et sp. nov. is represented by up to three orders of interconnected vegetative and fertile shoots that are preserved as coalified compressions with cuticles; some also display internal anatomy. The plant has an orthotropic stem, with two orders of plagiotropic lateral branches that all bear helically arranged simple leaves. Ovulate fructifications consist of compact zones of bracts with axillary ovuliferous dwarf shoots on otherwise vegetative branches. Pollen cones are compound shoots comprising helically arranged dwarf shoots in the axils of bracts on a main axis. Polliniferous dwarf shoots produce sterile scales, sporophylls with a terminal pollen sac, and in situ Potonieisporites grains. Stems have an endarch ...

Heracleum Mantegazzianum Sommier & Levier

Biennial or perennial monocarpic herb. Root pale yellow, bruising brown and exuding a sickly yellow sap from the cut surface; tap-root, 45-60 cm, initially narrow, becoming thicker and more divided with age, the crown reaching up to 15 cm in diameter at flowering. Lateral branches spreading horizontally or spirally from the often multiple tap-root; laterals suppressed in dense stands. The exocortex of the main root contractile from the first seedling leaf stage, the crown of adult plants ultimately positioned 8-12cm below ground level, deeper where sediments have accumulated after flooding. Older plants develop a solid stem-like stock, with old leaf scars, between the true root and the stem base. Stem single, annual, up to 0cm thick at base and 200-500cm tall, hollow, ridged, with purple blotches decreasing towards the top. Stem and petioles clothed with pustulate bristles, dense in the young state, more sparse after elongation. Leaves alternate, lower up to 250-300 cm, blades ternately or pinnately divided to a varying extent, coarsely and irregularly deeply lobed: lobes and larger teeth long-acuminate, usually puberulent below and more or less glabrous above; petiole stout, fleshy, hollow, more or less hairy, shortly sheathing at the base. Upper leaves progressively smaller, with a greatly inflated sheathing petiole to almost sessile, becoming increasingly bracteate higher up the stem. Flowers in compound umbels up to 80 cm across with 50-150 somewhat unequal hairy rays (15-40 cm). Rays shortest in the centre and longest at the edge of the umbel bringing all secondary umbels to a similar subspherical plane. Central ray vertical and distinct in main and branch terminal umbels, the remainder progressively curved centrifugally. Compound umbels on a short stem-like hollow peduncle, subtended by bracts. The terminal umbel is largest and hermaphrodite, surrounded by up to eight satellite umbels on elongated curving stalks raising them up to 40cm above the level of the terminal umbel. Additional terminal umbels may be borne on the main axillary branches which develop from the base of the main stem upwards; however, other umbels can develop from any of the remaining leaf or bract axils, especially on large vigorous plants or where the growth point of the main stem becomes damaged. Under stress, umbels may be degenerate and sterile. Umbels mature in sequence, the lower umbels smaller and sometimes male. Bracts usually several, linear or ovate and long acuminate; bracteoles linear, caducous. Pedicels 10-20 mm, hairy. Flowers white or rarely pinkish, sepals triangular, calyx teeth prominent, acute. Petals up to 12mm, outer petals radiating, styles with enlarged base forming the stylopodium. Styles about three times the length of the stylopodium, divergent or somewhat recurved. Stigma capitate. Pollen grains range from 56 to 77 ,m long (Grace & Nelson 1981). Fruit elliptical 6-18mm long, 4-10mm wide, typically 15mm long, 8 mm wide in large fruits, 8 mm long, 6 mm wide in small fruits, e.g. from the satellite inflorescences. Fruits usually glabrous to villous, dorsally much compressed; commissure broad. The fruit splits into two winged mericarps. Mericarp with slender, low dorsal ridges and rather broadly winged lateral ridges; the wings are flat and closely appressed to one another; carpophore present. The mericarp has three to five, usually four, conspicuous solitary claviform vittae (oil ducts), dark brown on the outer wall, approximately two-thirds as long as the mericarp and usually 0.51.0mm wide at the lower end (Tutin 1980) and two smaller vittae on the inner wall. The endosperm is oily and mature fruits have a strong resinous smell. Mericarp mass variable, ranging from a mean dry weight of 5.7mg (Grime et al. 1981) to 11.9-12.7mg dry weight from a population in Sheffield (J. Hodgson personal communication), 16.5mg the average dry weight in a population in the Lea Valley, London (range 4.6-23.2mg) to 18.2mg the average weight from a terminal umbel of a plant in west Scotland. The seed size and weight depend on the vigour of the plant and hierarchy of the umbel and are normally largest in the terminal umbel. Size and weight, but not necessarily viability, are reduced in the satellite and lower order umbels and in those late developing. The cotyledons are abruptly contracted into a petiole. *Abbreviated references are used for many standard works: see Journal of Ecology (1975), 63, 335-344. Nomenclature of vascular plants follows Flora Europaea and, where different, Stace (1991). ? 1996 British Ecological Society

Inflorescence and Floral Development in Orchidantha maxillarioides (Lowiaceae)

The inflorescence of Orchidantha maxillarioides is similar to a richly branched, polytelic truncate synflorescence. It consists of two to three paracladia borne in the axils of the uppermost phyllomes of the shoot. Each paracladium consists of six bracts. The lowermost bract is the sterile prophyll. The second and third bracts subtend paracladia of the next higher order. The fourth bract subtends a single flower. The fifth and sixth bracts are initiated but do not complete development. Initiation of the paracladia in the axils of bracts 2 and 3 is acropetal, but their differentiation is basipetal. The flowers are trimerous, with a perianth differentiated into sepals and petals. One petal is enlarged to form a labellum. There are five stamens, one inserted opposite each perianth member except the labellum. The ovary is inferior and is closed by a prolongation many times the length of the locular region of the ovary. Floral organ initiation begins with the posterior sepals. The anterior sepal is formed slightly later, at the same time as the initiation of the corolla. The anterior petals arise from primordia that produce only these organs, while the posterior petal (the labellum) arises from a common petal/stamen primordium. The petal/stamen primordium separates into the labellum and the two posterior outer stamens. The anterior outer stamen is initiated slightly later, in the region between the anterior petals. Throughout these stages a floral cup forms below the floral parts. The two inner stamens are initiated simultaneously on the inner surface of this cup, near the insertion of the anterior petals. Three gynoecial primordia are initiated at the top of the floral cup in the region that will form the prolongation. The primordia extend proximally to form the ovary proper and distally to form the style and stigma. The prolongation is formed through intercalary growth. Based on structural and functional similarities in the prolongation and inflorescence, we support placement of the Lowiaceae as the sister group of the Strelitziaceae.

Clonal Propagation of Pink Ginger in Vitro

Fig.1.Bractaxil explant (left) and rooted shoot with basal buds (right) of A. purpurata ‘Ginoza Hybrid No. 5’ on agar medium. Until the late 1980s, there were basically five clones of red and pink gingers [Alpinia purpurata (Veill.) K. Schum.] (Criley, 1988a), with the majority of the production being the red A. purpurata (no cultivar name) and its pink cultivar Eileen McDonald. These gingers primarily are propagated by division or by rooting aerial offshoots produced in the axils of the inflorescence bracts (Criley, 1988b). In 1985, however, Janet Ginoza, a commercial flower grower on the island of Oahu, found a seed pod on a plant of ‘Eileen McDonald’ and grew 20 seedlings from it (Hirano, 1991). The suspected pollen parent was the light-pink ‘Jungle Queen’. While ‘Eileen McDonald’ produces aerial offshoots in the inflorescence, ‘Jungle Queen’ does not, and most of the progeny, which had contrasting pink bracts with darker pink margins, also did not produce aerial offshoots. Three new superior cultivars have been named and released. Their propagation is slow, however, since division of the rhizome mat is the only available method. The objective of this research was to develop an in vitro multiplication system for rapid increase of these new clones. Twenty bract axils (Fig. 1) with associated dormant buds were excised from an inflorescence of ‘Ginoza Hybrid No. 5’ in Oct. 1988 and disinfested by placing individual 0.5-cm inflorescence axis sections with the bract base and vegetative axillary bud in 0.5% sodium hypochlorite plus one drop of Tween20 (Sigma Chemical Co., St. Louis) per 100 ml of diluted solution. After 10 rein, the axis was removed and trimmed to a cube 4 mm on each side, to include the bud, and placed in 0.25% sodium hypochlorite plus one drop of Tween 20 per 100 ml of diluted solution for 15 rein, followed by a 5-min sterile water rinse. As evidenced by

FLORAL ONTOGENY IN SOPHOREAE (LEGUMINOSAE: PAPILIONOIDEAE). I. MYROXYLON (MYROXYLON GROUP) AND CASTANOSPERMUM (ANGYLOCALYX GROUP)

Floral ontogeny is described and documented using scanning electron microscopy in Myroxylon balsamum and Castanospermum australe, representatives respectively of Polhill's Myroxylon and Angylocalyx groups (Leguminosae: Papilionoideae), groups exhibiting relatively unspecialized flower structure for the tribe Sophoreae. Both are woody tropical trees with axillary or terminal racemes or panicles. Bracteoles are present in both Myroxylon and Castanospermum. Flowers are initiated singly in bract axils, which are produced in acropetal order by the inflorescence apical meristem. The flower structure of both includes a broad calyx tube, five petals lacking any fusion (only the vexillary distinctive), ten free homogeneous stamens in two whorls, and a long‐stipitate carpel. The two taxa are alike in early organogenetic stages with essentially acropetal order of initiation: sepals, petals, outer stamens plus carpel, inner stamens. Within each whorl the order is unidirectional from the abaxial side. They are alike through middevelopment with one exception. There is accelerated vexillar enlargement in Castanospermum by middevelopment, not found in Myroxylon. Both have a hypanthium, which forms late in development. In both, large flower size, exserted stamens, and hypanthium are adaptations to bird‐pollination. Differences between the two that are manifested in late development include strongly zygomorphic calyx and petal color change over time (Castanospermum), stamens sagittate and apiculate with some basal filament fusion (Myroxylon), stigma form differences, and fruit form.

In vitro flowering of Japanese pear and the effect of GA 4+7

Flower formation of some Japanese pear cultivars, differing in the extent of apical dominance, was studied in relation to young-leaf removal (removing apical dominance) and in vitro vegetative apex culture. In all cultivars, removal of young leaves and disbudding promoted flowering in the remaining axillary buds on the long shoots as compared with only disbudding. The degree of promotion, however, remained within their flowering capacities, indicating that this capacity is inherent in the bud itself. Explants cultured in vitro formed flowers in the bract axils of their main shoot, regardless of whether they were prepared from the shoot apex or the axillary leaf bud. Occurrence of flowering in the explants was closely related to the flowering capacity characteristic of the cultivar from which they were derived. Flowering occurred predominantly in the explants with a particular range of node number, above or below which it decreased rapidly. The presence of gibberellin GA 4+7 in the medium tended to decrease flowering of explants, but had no effect on their node number.

Suchoviella—Gen. nov. from the permian of angaraland and a review of the systematics of cordaitanthales

Suchoviella synensis gen. et sp. nov. (Rufloriaceae) from the Upper Permian of the Pechora Fore-Urals is described. Its polysperms have an unbranched axis, bearing helically arranged short stalks in the upper part and at the base a rosette of sterile scales of the Lepeophyllum type. It is suggested that S. synensis, the dispersed seeds Samaropsis synensis (Dombrovskaya) comb. nov., the leaves Rufloria synensis (Zalessky) S. Meyen and the microstrobili of the Pechorostrobus S. Meyen type are parts of the same plant. A system of genera is proposed for male and female fructifications of Euramerian cordaitanthaleans of various modes of preservation. Identification of genera of male fructifications is established mainly on the structure of their sporangiophores and microsporangia as follows: unbranched or once-forked sporangiophores with microsporangia arranged in bunches, microsporangia with a longitudinal dehiscence slit — the genus Florinanthus gen. nov.; simple sporangiophores with microsporangia arranged in one row, microsporangia without specialized dehiscence mechanism or with longitudinal dehiscence slit — the genus Lesqueranthus gen. nov. Genera of female fructifications are based mainly on the structure of their seed stalks and axillary complexes. Forms with solitary seeds in the axils of bracts are recognized as Grandeuryconus gen. nov. Fructifications with seeds on short seed stalks, located amongst the scales of the axillary complex, are attributed to Renaulticonus gen. nov., whilst fructifications with long seed stalks branching in various planes and producing more than one seed are attributed to Procordaiconus gen. nov. The genus Rothwelliconus gen. nov. includes forms with long unbranched (or infrequently apically once-forked) seed stalks with, as rule, solitary seeds. It is suggested that Gothania Hirmer should be retained for permineralized fructifications of indefinite sex, whereas such fructifications in compression-impression material may be attributed to Cordaitanthus O. Feistmantel. Transfer of characters from one sex to the other is regarded as having been a possible mechanism for acquiring strobiloid organization in the male fructifications of cordaitanthaleans.

Scanning Electron Microscope Examination of Flower Bud Differentiation in Sour Cherry1

Abstract Axillary buds on ‘Montmorency’ sour cherry (Prunus cerasus L.) shoots were examined by scanning electron microscopy. On June 10, 4 weeks after anthesis, a doming of the apex signified the initial change from the vegetative to the reproductive stage. Flower primordia differentiated acropetally in the axils of bracts between late June and mid-July. Bract and flower primordia formed until all available space on the apex was occupied. Flower primordia changed from ovate to round as development proceeded. Sepal primordia were evident on July 30, 11 weeks after anthesis, and petal primordia had formed by August 15. Concentric rings of stamen primordia then developed followed by carpel differentiation in early September.