Polyaxial development in homeotic flowers of three begonia cultivars

1997 ◽  
Vol 75 (1) ◽  
pp. 145-154 ◽  
Author(s):  
Naida L. Lehmann ◽  
Rolf Sattler
Keyword(s):  
Key Words ◽  
Floral Development ◽  
Staminate Flower ◽  
Floral Buds ◽  
Floral Apex ◽  
Double Flowering ◽  
Begonia Semperflorens

Development of staminate flowers in double-flowering Begonia semperflorens-cultorum cultivars 'Cinderella', 'Goldie Locks', and 'Lucy Lockett' was examined using epi-illumination microscopy, focussing on later stages when secondary partial floral buds formed on the floral apex. This process, switching from floral to inflorescence-like development, is an example of homeosis, the expression of inflorescence features on a floral apex. Floral development began as in a normal begonia flower with the formation of a perianth consisting of two sepals and two petals, but sepaloid and (or) petaloid appendages then developed in what corresponded to stamen positions in normal Begonia species. This was usually followed by lateral elongation, distortion of the primary floral apex, and formation of secondary partial floral buds. The pattern of primordial inception on the secondary apices tended to be irregular, but in some cases, appendage primordia formed in groups of twos, threes, and fours, and in a somewhat alternating formation on the apices. Often, primordial initiation seemed to continue on secondary apices even after anthesis of the staminate flower. Appendage primordia that formed on the secondary buds usually were laterally elongate and bifacial, giving them a phyllomic appearance. Others were, on occasion, more hemispherical at inception, but as they developed they became phyllomic. Key words: homeosis, polyaxial, floral development, intermediate inflorescence.

Staminate floral development in Begonia cucullata var. hookeri and three double-flowering begonia cultivars, examples of homeosis

1996 ◽  
Vol 74 (11) ◽  
pp. 1729-1741 ◽  
Author(s):  
Nalda L. Lehmann ◽  
Rolf Sattler
Keyword(s):  
Floral Development ◽  
Staminate Flower ◽  
Double Flower ◽  
Stages Of Development ◽  
Early Stages ◽  
Double Flowering ◽  
Begonia Semperflorens

Homeosis is a process whereby features characteristic of one structure are found in the position that a different structure normally occupies. In three double-flowering begonia cultivars, perianth features are expressed in the positions stamens occupy in a single-flowering begonia. The staminate flower of Begonia cucullata var. hookeri (Willd.) consists of two broad sepals, two small petals in a more or less decussate arrangement, and an androecium of numerous stamens. The staminate flowers of Begonia semperflorens-cultorum ‘Cinderella’, ‘Goldie Locks’, and ‘Lucy Lockett’ also have a perianth of two sepals and two petals, but sepaloid and petaloid appendages form in positions that stamens occupy in the single-flowered progenitor. Using epi-iilumination microscopy, we found that early stages of floral development in the double-flowering cultivars are similar to the early stages of development in the single-flowered begonia, while later stages diverge remarkably. The first primordia that will form petaloid appendages are small and round at the time of initiation, similar in appearance and position to those primordia that become stamens in the single-flowered begonia. As these primordia develop, they broaden and flatten, forming perianth-like appendages. Keywords: homeosis, begonia, double flower, floral development.

Floral development of two species of Stylidium (Stylidiaceae) and some remarks on the systematic position of the family Stylidiaceae

1992 ◽  
Vol 70 (2) ◽  
pp. 258-271 ◽  
Author(s):  
Claudia Erbar
Keyword(s):  
Key Words ◽  
Floral Development ◽  
Floral Biology ◽  
Systematic Position ◽  
Inferior Ovary ◽  
Stamen Primordia ◽  
Floral Apex ◽  
The Family ◽  
Transversal Plane

The early floral development of Stylidium adnatum and Stylidium graminifolium is characterized by an initial circular primordium whose areas in the transversal plane of the floral primordium show enhanced growth. The spiral inception of the five sepals starts before the differentiation of the initial circular primordium into two stamen primordia in transversal position (in relation to the floral diagram) and the corolla ring primordium below the stamen primordia. Then five petal primordia, which alternate with the sepals, arise on the corolla ring primordium (early sympetaly). Peculiar to the flowers of Stylidiaceae is the column that bears at its top both stigma and anthers. Probably this column should be interpreted as a receptacular tube. No distinct carpel primordia have been observed. The inferior ovary results from intercalary growth in the peripheral parts of the receptacle below the calyx, corolla, and stamen primordia. The residual floral apex gives rise to a transversal septum, by which the ovary becomes bilocular. None of the morphological, palynological, and embryological characters discussed contradicts a position of the Stylidiaceae near the Campanulales, and several of these characters support this position. Key words: Stylidiaceae, Campanulales, floral development, systematic position, floral biology.

Floral development of Najas flexilis

1976 ◽  
Vol 54 (10) ◽  
pp. 1140-1151 ◽  
Author(s):  
U. Posluszny ◽  
R. Sattler
Keyword(s):  
Floral Development ◽  
Staminate Flower ◽  
Pistillate Flower ◽  
Axillary Meristem ◽  
Short Style ◽  
Najas Flexilis ◽  
Floral Apex ◽  
Cell Layers ◽  
The One ◽  
Floral Bud

Two subopposite leaves form at a node. The lower one arises almost simultaneously with the axillary meristem which it subtends. The upper leaf initiates after the lower one and does not subtend any structure. The axillary meristem gives rise to a renewal growth apex and a floral bud almost at its inception. In some cases the axillary meristem forms only a floral bud. The floral bud may be either staminate or pistillate. The main axis and the renewal growth in the axil of the lower leaf repeat this pattern of development. Staminate and pistillate flowers are almost indistinguishable at inception. They form as dome-like protuberances and both initiate girdling primordia, which become lobed at or immediately after inception. In the staminate flower the girdling primordium becomes the outer envelope, while a second girdling primordium formed acropetally becomes the inner envelope. Both envelopes overgrow the one-celled anther, which is the transformed staminate floral apex. In the pistillate flower the girdling primordium becomes the gynoecial wall that encloses the single bitegmic ovule, which is the transformed pistillate floral apex. On a short style a stigma with two to four branches develops. The renewal growth apices have a one-layered tunica. The two subopposite leaves are initiated through cell division in both tunica and corpus cells. The axillary meristem arises through periclinal divisions in the corpus cells. The girdling primordia of both staminate and pistillate floral buds are epidermal in origin as are the integuments of the ovule. Procambial development is acropetal following closely primordia inception. Each leaf, floral bud, and renewal growth apex receives a single strand. No vascularization is seen in envelopes of the staminate flower or the gynoecial wall of the pistillate flower, all of which remain two cell layers thick even at maturity.

Response of lowbush blueberry (Vaccinium angustifolium) to hexazinone applied early in the fruiting year

2002 ◽  
Vol 82 (4) ◽  
pp. 781-783 ◽  
Author(s):  
K. I. N. Jensen ◽  
E. G. Specht
Keyword(s):  
Key Words ◽  
Weed Control ◽  
Corolla Tube ◽  
Growth Stages ◽  
Vaccinium Angustifolium ◽  
Floral Buds ◽  
Perennial Weeds ◽  
Lowbush Blueberry ◽  
Herbaceous Perennial

Spring application of 1.0 kg ha-1 hexazinone to fruiting-year lowbush blueberry no later than the F3 floral stage, when floral buds separate, but before the corolla tube shows white, controlled some common herbaceous perennial weeds without injury to the crop. Key words: Herbicide injury, growth stages, weed control, hexazinone, Vaccinium angustifolium

Floral development of Rosa setigera

1993 ◽  
Vol 71 (1) ◽  
pp. 74-86 ◽  
Author(s):  
James R. Kemp ◽  
Usher Posluszny ◽  
Jean M. Gerrath ◽  
Peter G. Kevan
Keyword(s):  
Key Words ◽  
Floral Development ◽  
Functional Approach ◽  
Floral Meristem ◽  
Cryptic Dioecy ◽  
Congenital Fusion ◽  
Postgenital Fusion

The development of the flower of Rosa setigera from initiation to the onset of anthesis is described. Rosa setigera is the only known member of the genus Rosa to exhibit dioecy. Flowers of functionally staminate (male) and functionally carpellate (female) plants appear identical, a condition referred to as cryptic dioecy. Discrete sepals and petals are formed on the floral meristem. As the hypanthium forms, stamens are initiated in alternating whorls on the wall of the hypanthium and continue to develop as the hypanthium extends. Carpel primordia arise individually on the remainder of the floral meristem and show neither adnation to the hypanthial wall nor coalescence to one another as they give rise to the styles and stigmas that are exserted above the hypanthium lip. The only observable fusion in this species appears to be the postgenital fusion of the margins of the carpel primordia to form the enclosed locule. Although historically the hypanthium has been variously interpreted as either axial and (or) appendicular in nature, resulting from congenital fusion of sepals, petals, and stamens, this paper uses a more realistic, testable and functional approach to the development of the hypanthium that is in keeping with current concepts such as process morphology. Key words: Rosa setigera, dioecy, floral development, fusion, hypanthium.

Aspects of inflorescence and floral development in the putative basal angiosperm Amborella trichopoda (Amborellaceae)

2003 ◽  
Vol 81 (1) ◽  
pp. 28-39 ◽  
Author(s):  
Usher Posluszny ◽  
P Barry Tomlinson
Keyword(s):  
Floral Development ◽  
Close Packing ◽  
Basal Angiosperm ◽  
Size Difference ◽  
Tunica Layer ◽  
Flat Base ◽  
Floral Apex ◽  
Rapid Transition ◽  
Basal Meristem ◽  
Female Flowers

Amborella has woody axes whose development is intrinsically plagiotropic and determinate. The tree habit is achieved through overtopping of older axes by basally produced younger axes, as in Mangenot's model. Inflorescence units, which are produced in the axils of distal leaves, may be described as extended cymes, each branch ending in a flower. Basal bracteoles have a decussate arrangement, which is modified to an alternate phyllotaxis distally. Flowers produce one or more additional bracteoles with a rapid transition to the spiral phyllotaxis of the broad overlapping tepals. In this transition the initially conical floral apex becomes invaginated to form a floral cup, with subsequent appendages appearing on its inner margin. The floral apex then forms the flat base of the cup but retains a discrete single tunica layer. The receptacular bowl is deepened and narrowed by the basal meristem of each appendage, the last formed floral organs usually consuming the floral meristem. Sexual parts are more numerous in male than female flowers, accounting for their size difference, but primordia of stamens and carpels are initially very similar. Floral symmetry is largely a consequence of close packing of appendages within the floral cup. In its initial stages of development the flower does not conform to any conventional floral model in angiosperms and is better regarded as highly specialized rather than ancestral in its synorganization. This is not unexpected in a lineage of such long independent evolution.Key words: Amborella, basal angiosperm, development, inflorescence, primitive flower.

Shoot ontogeny in Fraxinus pennsylvanica (green ash). II. Development of the inflorescence

1989 ◽  
Vol 67 (7) ◽  
pp. 1966-1978 ◽  
Author(s):  
W. R. Remphrey
Keyword(s):  
Fruit Set ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Dioecious Species ◽  
Male And Female ◽  
Floral Buds ◽  
Growing Seasons ◽  
Female Inflorescence ◽  
Mature Flower ◽  
Floral Apex

From initiation to fruit set, which occurs over three growing seasons, eight stages are recognized in the development of axillary inflorescences in the dioecious species Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern, (green ash). In the first season, buds are initiated in the axils of foliage leaves. As the shoots expand in the following spring, the buds complete their development. Although similar at first, differences begin to emerge between vegetative and inflorescence buds in that the latter produce robust second-order meristems, the incipient paracladia, protruding close to the original apex. After about 3–4 weeks, when the initiation of such buds is complete, the terminal and subtending lateral meristems present on each axis develop into a three-membered cluster of floral buds. There was a mean of 214.3 ± 12.2 floral buds initiated per female inflorescence, and the number generally increased with the length of the associated shoot. A ridge, the incipient perianth, begins to form around the periphery of each rounded floral apex. Male and female floral buds are not distinguishable at this stage, but the inflorescence buds are distinctly different from vegetative buds. The male and female buds then diverge in their development in that an identation forms at the summit of the incipient gynoecium and male buds initiate two or three anthers. By autumn, the gynoecium is distinctly conical, with an orifice at its summit, and the anthers are lobed. There is lobing of the perianth ridge, but in the mature flower distinct organs traceable to such lobes could not readily be identified.

A technique for the study of floral development

1968 ◽  
Vol 46 (5) ◽  
pp. 720-722 ◽  
Author(s):  
Rolf Sattler
Keyword(s):  
Floral Development ◽  
Developmental Stages ◽  
Three Dimensional ◽  
Serial Sectioning ◽  
Direct Study ◽  
Floral Buds ◽  
Dimensional Picture

When floral buds are studied by serial sectioning, the obtained three-dimensional picture of the buds is a reconstruction which involves some theoretical elements. In contrast to this reconstructive method, the described technique permits the direct study of the three-dimensional developmental stages of flowers. Protoderm cells of floral apices and primordial appendages can be demonstrated.

Floral development of Myrica gale and the controversy over floral concepts

1973 ◽  
Vol 51 (10) ◽  
pp. 1965-1975 ◽  
Author(s):  
Alastair D. Macdonald ◽  
Rolf Sattler
Keyword(s):  
Floral Development ◽  
Vascular Tissue ◽  
A Priori ◽  
Median Plane ◽  
Layer Growth ◽  
Myrica Gale ◽  
The Third ◽  
Cell Divisions ◽  
Floral Apex ◽  
Upward Growth

Two bracteoles form by divisions in the second layer of cells on the transversal flanks of the floral apex. Four stamens form in the male by cell divisions in the third layer of cells; one develops opposite each bracteole and two form in the median plane on either side of the floral apex. In the female bud a girdling gynoecial primordium forms by periclinal divisions in the second layer. Growth becomes localized in two or three zones in the gynoecial primordium; upward growth results in the formation of two or three stigmas. The gynoecial wall forms by intercalary growth above and below the region of bracteole attachment. The ovule develops by the resumption of growth of the floral apex. A single vascularized integument, formed at first by periclinal divisions in the protoderm, encloses the nucellus. The development and pattern of the vascular tissue is described. Four conceptual frameworks regarding the morphological nature of the flower are outlined and the data derived from this study are analyzed in relation to each framework. The interpretations are conflicting and it is considered that this is due, in part, to an a priori establishment of mutually exclusive categories.

Floral development in Melaleuca and Callistemon (Myrtaceae)

1998 ◽  
Vol 11 (6) ◽  
pp. 689 ◽  
Author(s):  
D. A. Orlovich ◽  
A. N. Drinnan ◽  
P. Y. Ladiges
Keyword(s):  
Floral Development ◽  
Flower Bud ◽  
Variable Expression ◽  
Total Absence ◽  
Stamen Primordia ◽  
Intermediate Morphology ◽  
Floral Apex

Floral development of seven species of Melaleuca and four species of Callistemon is compared. The multistaminate fascicles of Melaleuca develop from stamen primordia initiated on antepetalous pre-staminal bulges (PSBs); the resultant bundles of stamens become separated by hypanthial expansion as the flower bud enlarges. In most species of Callistemon examined the stamen primordia are initiated directly on the floral apex, and the stamens are distributed evenly around the hypanthium at anthesis. The possession of large and prominent PSBs, and thus stamen fascicles, is a feature of most species of Melaleuca and their total absence is a feature of most species of Callistemon; however, there is a continuum between these two extremes. Several taxa of both genera exhibit intermediate morphology. In C. glaucus (Bonpl.) Sweet, small but distinct PSBs develop, which influence antepetalous stamen groups that remain contiguous at anthesis. This also occurred in M. leucadendra (L.) L. This variable expression of PSBs is the result of differences in the timing of stamen initiation. Other variable features are determined by the space available for primordium initiation and the patterns of growth and expansion of the developing flower.

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