Search results for "Primordium"

Ongoing Evolution in the Genus Crocus: Diversity of Flowering Strategies on the Way to Hysteranthy

2021

[EN] Species of the genus Crocus are found over a wide range of climatic areas. In natural habitats, these geophytes diverge in the flowering strategies. This variability was assessed by analyzing the flowering traits of the Spanish collection of wild crocuses, preserved in the Bank of Plant Germplasm of Cuenca. Plants of the seven Spanish species were analyzed both in their natural environments (58 native populations) and in common garden experiments (112 accessions). Differences among species observed in the native habitats were maintained under uniform environmental conditions, suggesting a genetic basis for flowering mechanisms. Two eco-morphological types, autumn- and spring-flowering …

‘False resupination’ in the flower-pairs of Thalia (Marantaceae)

2016

Abstract Resupination, i.e., the turn by 180°, arranges zygomorphic flowers in a suitable position for pollination. It is well-known from orchids, but also occurs in further angiosperm families. Within the genus Thalia L. (Marantaceae), T. dealbata has erect and T. geniculata pendulous inflorescences. Nevertheless, in both species the zygomorphic flower-pairs show the right position for pollination. Thus, resupination is expected in Marantaceae. To reconstruct spatial arrangement, flower development was investigated from meristem formation to anthesis. Early morphogenetic stages were analysed under the scanning electron microscope, late stages were documented by time-lapse records. Gravity …

Patterns of flower development in Apiaceae–Apioideae

2016

Abstract Apiaceae is a large family characterized by uniform flowers. However, early ontogenetic studies revealed unexpected diversity in flower development. In the present paper, we investigate eight species representing six tribes of subfamily Apioideae to address diversity in developmental patterns. One focus is on the developmental divergence of sex morphs in andromonoecious species. Scanning electron microscopic studies were conducted on six herbaceous species: Chaerophyllum bulbosum , Daucus carota , Dorema aucheri , Ferula hezarlalehzarica , Orlaya grandiflora , Pastinaca sativa , and two woody species, i.e., Bupleurum fruticosum and Seseli ghafoorianum . Our results confirm the exis…

2017

The genus Dipsacus is characterized by a remarkable bidirectional flowering sequence and a rare phyllotactic pattern. Considering that flower initiation and flowering sequence may be interconnected, we document the development of the head meristem in Dipsacus fullonum. Our results indicate a gradual change in the geometry of the head meristem beginning with a dome shaped stage, continuing with a remarkable widening in the middle part of the head meristem and ending in a spindle-like form. Quantitative data confirm that meristem expansion is higher in the middle part than at the base of the meristem. Likewise, the size of the flower primordia in the middle part of the young head is significa…

The role of heterochrony in Schizanthus flower evolution- a quantitative analysis

2021

Abstract Changes in the timing of development within a lineage (heterochrony) have an enormous impact on floral diversification. However, comparative quantitative studies in a broad range of ontogenetic stages are still needed to identify the role of different heterochronic processes shaping diversification patterns. In this study, changes in petal development were compared across species in the genus Schizanthus showing floral diversification mediated by pollinators. In this genus, transitions from bee- to hummingbird- and moth- pollination are associated with lower lip diversification. Variation in size and shape of petals was quantified at key ontogenetic stages by using a traditional an…

2017

Diversification in flower shape and function is triggered by the high plasticity of flower meristems. Minute changes in space and time can profoundly affect the formation of adult structures. Dipsacoideae provides an excellent model system to investigate the evolutionary aspects of temporal and spatial changes in flower development due to its small size, the resolved phylogenetic framework, and significant diversity of perianth form and merosity. In the present study, we investigated the sequence of floral organ initiation and quantified the interactions between flower meristem expansion and petal primordium size in eight species representing two major clades of Dipsacoideae. Our quantitati…

EcFLO, a FLORICAULA-like gene from Eschscholzia californica is expressed during organogenesis at the vegetative shoot apex.

2003

FLORICAULA/ LEAFY-like genes were initially characterized as flower meristem identity genes. In a range of angiosperms, expression occurs also in vegetative shoot apices and developing leaves, and in some species with dissected leaves expression is perpetuated during organogenesis at the leaf marginal blastozone. The evolution of these expression patterns and associated functions is not well understood. We have isolated and characterized a FLORICAULA-like gene from California Poppy, Eschscholzia californica Cham. (Papaveraceae), a species belonging to the basal eudicot clade Ranunculales. EcFLO encodes a putative 416-amino-acid protein with highest similarity to homologous genes from Trocho…

Untersuchungen zur biologischen Aktivität der Phenylborsäure

1961

After 10 applications of phenylboric acid (0.03 ml of a 2·10−3 M solution) to young plants ofKalanchoe blossfeldiana the flowers were found to have a reduced number of petals or no petals at all. InCucumis sativus one application of phenylboric acid at the same strength was enough to cause abnormal flowers to develop in the axils of 8 to 10 leaves; in addition there were 1 to 2 leafles nodes and other abnormalities. The position of the abnormal flowers and leafless nodes was dependant upon the stage of development of the plant at the time of application. It seems from a parallel study of treated plants grown to maturity, and plants sectioned at the time of treatment, that phenylboric acidin…

The architecture ofMourera fluviatilis(Podostemaceae): developmental morphology of inflorescences, flowers, and seedlings

1999

Mourera fluviatilis from northern South America is a spectacular member of the Podostemaceae (river-weeds). Its racemelike inflorescences are up to 64 cm long and have 40‐90 flowers arranged in two opposite rows. Inflorescence development starts with the initiation of a double-sheathed (dithecous) bract in a terminal position. All lateral bracts (again dithecous) are initiated in basipetal order along the two flanks of the inflorescence. Each gap between two neighboring bracts contains a single flower. The flowers are bisexual, each with a whorl of 16‐20 ligulate tepals and 14‐40 stamens, which are arranged in one or two whorls. Floral development starts with the formation of a girdling pri…

Floral and Vegetative Morphogenesis in California Poppy (Eschscholzia californicaCham.)

2005

For studies of the evolution of development in angiosperms, early‐diverging eudicot taxa are of particular interest for comparisons with established core eudicot model plants, such as Arabidopsis. Here we provide a detailed description of shoot and floral development of the basal eudicot California poppy (Eschscholzia californica). Rosette formation in the vegetative phase is accompanied by increased leaf complexity and shoot apex size. The flowering phase is characterized by internode elongation, formation of dissected cauline leaves, terminal flowers, and basipetal inflorescence branching. For developing flowers and fruits, we have defined 14 stages according to important landmark events,…