Types of Androecium in the Fabaceae of SW Europe

We studied the morphology of the androecium in 168 species andsubspecies of Fabaceae from SW Europe and its relationship withnectar production. Six androecium types were recognized: monadelphous;pseudomonadelphous without basal fenestration; pseudomonadelphouswith basal fenestration; diadelphous; reduced diadelphous; andandroecium with free stamens. The monadelphous androecium appearsin the tribe Genisteae, inOnonis, and inGalega officinalis,andthe pseudomonadelphous without basal fenestration only in thegenusCoronilla,with both types having the same functionality—theyare linked to the absence of nectar from an intrastaminal nectary,their taxa being mostly polliniferous. The pseudomonadelphousandroecium with basal fenestration appears in around 38% ofthe taxa studied and has the same functionality as the diadelphousandroecium: there is nectar secretion from an intrastaminalnectary in both. The reduced diadelphous androecium only appearsin three species (Biserrula pelecinus, Vicia pubescensandAstragalusepiglottis), and its functionality could be related to the syndromeaccompanying autogamy in Angiosperms. The free stamen androeciummay imply a greater nectar production than other types.Copyright1999 Annals of Botany Company. Fabaceae, Leguminosae, androecium, nectar, floral biology.     

Floral Developmental Evidence for the Systematic Relationships of Tropaeolum(Tropaeolaceae)

The floral ontogeny of three species of Tropaeolum was studiedusing scanning electron microscopy to find morphological evidencefor discussing the systematic position of the family. The initiationof the androecium is highly unusual: there are always eightstamens which arise (1) either in a spiral sequence startingwith the stamen opposite sepal four, running in a directionopposite to the sequence of the sepals, and with reversals inthe direction of the spiral, or (2) as a sequence of pairedand unpaired stamens. The floral symmetry changes twice duringthe development of the flower, from polysymmetrical at sepaland petal initiation, through oblique monosymmetry at stameninitiation, and ending with median monosymmetry in later developmentalstages. The occurrence of median monosymmetry is a late-developmentalevent and is caused by the initiation of a hypanthial spur,and the unequal growth of the petals and styles. The originfor the unusual sequence of stamen initiation reflects a trendaffecting the whole flower which is linked with the changingpatterns of floral symmetry. Octandry is enhanced by multiplecauses, such as the loss of two stamens in an originally diplostemonousandroecium and the regulating pressure of the gynoecium. Thechange in symmetry during ontogeny is significant for discussingthe systematic position of Tropaeolaceae in comparison withthe glucosinolate-producing taxa and the Sapindales. The combinationof an androecium with eight stamens and oblique monosymmetryis either a single event in evolution and links Tropaeolum withthe Sapindales, or it has evolved at least twice, once in theSapindales, and once in a clade comprising Tropaeolaceae, Akaniaceaeand Bretschneideraceae. Morphological data support a sistergroup relationship of the three latter families, which is inline with macromolecular studies. Copyright 2001 Annals of BotanyCompany Tropaeolum, Tropaeolaceae, Glucosinolate clade, Sapindales, oblique monosymmetry, androecium, octandry, floral development, phylogeny     

Response of female melon fly, Bactrocera cucurbitae, to host-associated visual and olfactory stimuli

In a series of studies conducted in Hawaii under seminatural conditions, we quantified the response of sexually mature, host‐seeking female melon flies, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), to different types of visual and chemical host‐associated stimuli with the main aim of developing a monitoring device for females. Experiments were conducted using Tangletrap‐coated fruit mimics of either spherical (8 cm diameter) or cylindrical (4.3 cm diameter; 15 cm length) shapes coated with different artificial color pigments both at the ground level and at the tree‐canopy level so as to take into account the foraging behavior of adult melon flies. Females were particularly attracted to objects of spherical shape colored either yellow, white, or orange; these three pigments offered the highest reflectance values. Cucumber (Cucumis sativus L.) (Cucurbitaceae) odor was more attractive to females than odors of three other cultivated host fruit [zucchini, Cucurbita pepo L. var. medullosa Alef. (Cucurbitaceae); papaya, Carica papaya L. (Caricaceae); or tomato Solanum lycopersicum L. (Solanaceae)] or of ivy gourd [Coccinia grandis (L.) Voigt (Cucurbitaceae)], one of the major wild hosts of melon fly in Hawaii. A combination of both visual and olfactory stimuli was needed to elicit high levels of response compared to each stimulus offered alone. We discuss our results in relation to the potential implementation of improved female monitoring and/or attract‐and‐kill strategies for melon flies in Hawaii.     

Androecial Development in Six Polyandrous Genera Representing Five Major Groups of Palms

Floral organogensis is described for six polyandrous generarepresenting borassoid, caryotoid, ceroxyloid, inarteoid, andgeonomoid major groups of palms. In all, three sepals and threepetals arise from dome-shaped floral apices in alternate pseudo-whorls.After petal inception, the floral apex expands in a differentway in each major group. Different numbers and arrangementsof stamens develop in antesepalous (AS) and antepetalous (AP)positions Primary pnmordia are sometimes distinct, and stamenpnmordia vary in form In borassoid and caryotoid palms, AS whorlsalways consist of three stamens, but several stamens arise inthe lower, wider AP positions Ceroxylon is characterized bylarge primary primordia with two to three stamens developingopposite each petal and, in species with more than 12 stamens,two to three also opposite each sepal. Several stamens ariseon distinctive truncate, AS primordia in a definite patternthat is repeated in AP positions in inarteoid palms In polyandrousgeonomoid genera, stamens arise in AS and AP arcs on a flattrilobed floral apex. Previous work has shown similarities instamen inception in arecoid genera to that in borassoid andcaryotoid palms, and centrifugal initiation in all phytelephantoidpalms. All polyandrous taxa, except phytelephantoid palms, exhibita basic tnmery. The different patterns of apical expansion andstamen arrangement indicate that polyandry has arisen separatelyin each major group of palms. The mode of apical expansion andthe form of the primordia appear to depend on pressures imposedon the floral apices, suggesting that specialization of inflorescencebracts and perianth segments preceded the evolution of polyandry.Correlations of vasculature with developmental patterns areindicated. Lodoicea maldivica (Gmelin) Persoon, Caryota mitis Loureiro, Ceroxylon alpinum Bonpland ex DeCandolle, Socratea exorrhiza (Martius) H. Wendland, Wettima castanea Moore and Dransfield, Welfia georgii H. Wendland ex Burret, palms, androecium, stamen development     

Floral ontogeny and systematic position of the Didiereaceae

Floral ontogenetical data from all four genera of the Didiereaceae (s.str.) are presented for the first time. All Didiereaceae s.str. are dioecious, having unisexual flowers with organ rudiments of the opposite sex. Two median bracts followed by a tetramerous perianth (two alternating dimerous ``whorls'), a slightly complex androecium with 6–12 stamens in a single row (on a common ring primordium), four of which mostly alternating with the perianth members, and one basal ovule connecting three free septa at their very base are flower characters in Didiereaceae, supporting phylogenetic analyses based on nucleotide sequence data. Closest relatives are the (formerly) portulacaceous genera Portulacaria (5 stamens alternating with the perianth), Ceraria (5 stamens alternating with the perianth), and Calyptrotheca (many stamens), all with pentamerous perianths, from which the tetramerous perianth in Didiereaceae can be derived. Applequist and Wallace (2003) included these three genera in an expanded family Didiereaceae (with three subfamilies).     

Androecium and floral nectaries ofHarungana madagascariensis (Clusiaceae)

The mature flower ofHarungana madagascariensis (Choisy)Poir. has an androecium of five antipetalous fascicles, consisting of four stamens each. The stamen fascicles alternate with five indented nectary scales. A SEM-study of the floral development, as well as a study of the floral anatomy was carried out to understand whether the nectariferous scales represent staminodia or are receptacular in nature and consequently whether or not the androecium ofHarungana, and theClusiaceae in general, is originally diplostemonous. The five petals originate by the splitting of petal-stamen complexes. Next the upper part of each complex differentiates basipetally in four stamens. The stamens remain fascicled and are lifted on a long stalk at maturity. Five carpel primordia are initiated united in a low ringwall. The five nectary scales appear after carpel inception and develop an external morphology reminiscent of anthers. The floral anatomy reveals an independent origin of sepal median traces and common sepal lateral traces, free petal traces, stamen fascicle traces and alternating vascular tissue which supplies the nectaries. The petal-stamen complexes are the result of a retardation in petal inception, linked with the absorption of petal tissue into the stamen primordia. The development of the stamen fascicles is discussed; it is suggested that they are of a secondary nature and do not appear as a reduction from a multistaminate androecium. The external morphology and vascular anatomy of the scales speaks in favour of a staminodial nature. The comparison with some other species of theClusiaceae gives evidence of a diplostemonous ancestry of the androecium.     

Notes on the Evolution of Androecial Organisation in the Magnoliophytina (Angiosperms)

This paper aims to summarize briefly and to update our ideas about androecial architecture formulated in earlier publications. Ontogenetic evidence of stamen development, viz. the initiation, arrangement and relationship of stamens to other floral morphomes, can be translated into a semophyletic scheme reflecting the phylogeny of the androecium. The ancestral androecium is discussed in the light of recent theoriesabout angiosperm phylogeny. Two divergent androecial processes are proposed for the angiosperms starting from a spiral androecium with a moderate number of stamens. However, transitions exist between spiral polyandry, numerous stamens in whorls, and chaotic polyandry. From an androecium with several alternating whorls of paired and single stamens, outer stamen pairs are retained following the successive loss of inner stamen whorls. Single stamens instead of pairs occur at the very end of this line and represent a more advanced condition. This line is mostly present in tri- and dimerous flowers. From the same starting point diplostemony (with two alternating whorls of single stamens) originated, again giving rise to various states usually present in pentamerous or tetramerous flowers.     

FLORAL DEVELOPMENT AND VASCULATURE IN HYDROCLEIS NYMPHOIDES (BUTOMACEAE)

The flower of Hydrocleis nymphoides consists of three sepals which arise in spiral succession, three simultaneously arising petals, numerous stamens and staminodia which arise in centrifugal order, and six carpels. A residual apex remains at maturity. The first-formed members of the androecium are stamens and the later-formed members are staminodia which develop below the stamens and which become outwardly displaced during expansion of the receptacle. The androecium is supplied by branching vascular trunk bundles. The carpels are completely open but the ventral margins are slightly conduplicately appressed basally. A single dorsal bundle provides the stigmatic area with vascular tissue, and a network of small placental bundles supplies the numerous laminar ovules. There are no clearly defined ventral bundles. It is suggested that Hydrocleis nymphoides is neither the most primitive nor the most advanced member of the family. A pattern of phylogenetic reduction in the androecium and receptacle is suggested for the entire family.     

ONTOGENY AND ANATOMY OF THE FLOWER OF LIMNOCHARIS FLAVA (BUTOMACEAE)

The flowers of Limnocharis flava (L.) Buch. are borne in an indeterminate umbel and each consists of three sepals, three yellow petals, and about 18 carpels surrounded by numerous stamens and staminodia. The androecium is centrifugally developed, and the last-formed members are staminodial; it is supplied by branching vascular systems. Carpels arise almost simultaneously, and a prominent residual floral apex remains. The carpels are partially conduplicately closed and are also primitive in possessing laminar placentation and in lacking differentiation of a style. The gynoecium is essentially apocarpous, but there are slight fusions of adjacent carpels near their ventral margins where they are attached to the receptacle. It is suggested that the Limnocharis flower is the most primitive in the family.     

Scarlet gourdCoccinia grandis little-known tropical drug plant

Coccinia grandis (Cucurbitaceae), scarlet gourd, is widely distributed throughout the tropics and can be found in both wild and cultivated states on the plains of India. Although the sweet type is extensively cultivated for its edible fruits,C. grandis may have some potential value as a remedy for diabetes. A brief account of the botanical aspects and the food and the potential medicinal value of the different promising cultivars is provided.     

Floral ontogeny of Annonaceae: evidence for high variability in floral form

Background and Aims

Annonaceae are one of the largest families of Magnoliales. This study investigates the comparative floral development of 15 species to understand the basis for evolutionary changes in the perianth, androecium and carpels and to provide additional characters for phylogenetic investigation.

Methods

Floral ontogeny of 15 species from 12 genera is examined and described using scanning electron microscopy.

Key Results

Initiation of the three perianth whorls is either helical or unidirectional. Merism is mostly trimerous, occasionally tetramerous and the members of the inner perianth whorl may be missing or are in double position. The androecium and the gynoecium were found to be variable in organ numbers (from highly polymerous to a fixed number, six in the androecium and one or two in the gynoecium). Initiation of the androecium starts invariably with three pairs of stamen primordia along the sides of the hexagonal floral apex. Although inner staminodes were not observed, they were reported in other genera and other families of Magnoliales, except Magnoliaceae and Myristicaceae. Initiation of further organs is centripetal. Androecia with relatively low stamen numbers have a whorled phyllotaxis throughout, while phyllotaxis becomes irregular with higher stamen numbers. The limits between stamens and carpels are unstable and carpels continue the sequence of stamens with a similar variability.

Conclusions

It was found that merism of flowers is often variable in some species with fluctuations between trimery and tetramery. Doubling of inner perianth parts is caused by (unequal) splitting of primordia, contrary to the androecium, and is independent of changes of merism. Derived features, such as a variable merism, absence of the inner perianth and inner staminodes, fixed numbers of stamen and carpels, and capitate or elongate styles are distributed in different clades and evolved independently. The evolution of the androecium is discussed in the context of basal angiosperms: paired outer stamens are the consequence of the transition between the larger perianth parts and much smaller stamens, and not the result of splitting. An increase in stamen number is correlated with their smaller size at initiation, while limits between stamens and carpels are unclear with easy transitions of one organ type into another in some genera, or the complete replacement of carpels by stamens in unisexual flowers.     

Floral ontogeny of <Emphasis Type="Italic">Schisandra chinensis</Emphasis> (Schisandraceae): implications for androecial evolution within <Emphasis Type="Italic">Schisandra</Emphasis> and <Emphasis Type="Italic">Kadsura</Emphasis>

The organogenesis of staminate and carpellate flowers of Schisandra chinensis (Schisandraceae) was investigated with scanning electron microscopy, with observations on the development of tepals reported for the first time. The results showed that there is no interval between the initiation of the last tepal and that of the first stamen or carpel, and that the shapes of tepal, stamen, and carpel primordia are similar. The tepals and stamens of staminate flowers are initiated acropetally in a continuous spiral Fibonacci phyllotaxis, with no carpel structures observed; the filaments are not connate. The organogenesis of the carpellate flowers is similar to that of the staminate flowers, but with no evidence of stamen development. The carpels are ascidiate without postgenital fusion. Three androecial characters of Schisandra and Kadsura are discussed in a phylogenetic context. The subglobose or obovoid androecium of Schisandra propinqua and Schisandra plena may be homologous with that in sections Kadsura and Sarcocarpon. The plesiomorphic form of the androecium within the two genera is likely to be elongate with more than ten free stamens.     

Reevaluation of the perianth and androecium in Caryophyllales: implications for flower evolution

The Caryophyllales have the highest diversity in androecial patterns among flowering plants with stamen numbers ranging from 1 up to 4,000. Thanks to the recent progress in reconstructing the phylogeny of core Caryophyllales, questions of floral evolution, such as the origin and diversification of the androecium, can be readdressed. Caryophyllales are unique among core eudicots in sharing an androecial ring meristem or platform with centrifugal development of stamens and petals. Stamens are basically arranged in two whorls and evolution within the clade depends on the shift of either the antesepalous or the alternisepalous whorls to an upper position on the ring meristem and the reduction of the other. Four main developmental phenomena are responsible for the high diversity in androecial patterns: (1) the sterilisation of the outermost stamens through a division of common primordia; (2) the secondary addition of stamens by a centrifugal initiation of supernumerary stamens superimposed on a lower stamen number; (3) the pairwise displacement of alternisepalous stamens to the middle of the outer sepals and their potential fusion, or as part of a pluristaminate androecium; (4) the inversed sequence, reduction and loss of antesepalous stamens. Shifts in stamen numbers depend on pressures of the calyx and carpels and changes in the number of the latter. These patterns are expressed differently in the three main evolutionary lines of core Caryophyllales and are systematically relevant: (1) A basal grade of Caryophyllales, culminating with Caryophyllaceae, Amaranthaceae, Stegnosperma and Limeum, has the antesepalous stamens initiated in upper position on the ring meristem, and alternisepalous stamens are preferentially reduced. Among the antesepalous whorl there is a progressive loss of stamens following a sequence inversed to sepal initiation. Petaloid staminodes are formed by the radial division of outer stamens. (2) The raphide-clade and Molluginaceae are characterized by alternisepalous stamens in upper position on the ring meristem, with a trend to secondary stamen multiplication, and loss of antesepalous stamens. (3) The Portulacineae share the pattern of the raphide clade, but some taxa show shifts to an upper position on the ring meristem of either antesepalous or alternisepalous stamens, linked with secondary multiplications and reduction of either whorl. Different floral characters are plotted on a recent cladogram of Caryophyllales. The data show a consistent correlation between shifting carpel and stamen numbers independent of perianth evolution. Comparative data suggest that the basic androecium of Caryophyllales consists of two whorls of five stamens, linked with an absence of petals, and the evolution of the androecium is a combination of reductions and secondary multiplications of stamens with a highly predictive systematic value.     

Early floral development of Pentaphylacaceae (Ericales) and its systematic implications

Early floral development of four species from the genera Anneslea, Cleyera, Eurya, and Ternstroemia of Pentaphylacaceae, was studied comparatively using scanning electron microscopy. Together with earlier studies in Euryodendron and Adinandra, 6 out of 12 genera of Pentaphylacaceae have now been studied for their floral development. The usually pentamerous flowers of these taxa share a number of developmental features: the perianth organs appear in a clockwise or anticlockwise spiral sequence on the floral apex with relatively long plastochrons between successive organs, resulting in conspicuous size differences among perianth organs during early developmental stages. The early development of the usually polystemonous androecium is characterized by an indistinct ring-primordium and a mostly concave floral apex; individual stamens appear subsequently on this ring-primordium. However, further development of the androecium differs conspicuously among taxa and we describe three main developmental patterns for the family including features such as centripetal stamen whorls and stamens fascicles. Unusual features of floral development and organization of Pentaphylacaceae include: (1) a pronounced spiral sequence of organ appearance during early floral development in perianth and androecium; (2) the occurrence of paired organs in the corolla and the androecium of some species; (3) sepals and petals that are positioned opposite from each other in the genera Anneslea and Ternstroemia; and (4) a concave floral apex at the beginning of androecium development. From a systematic point of view our results clearly support a close relationship between Anneslea and Ternstroemia and also suggest a closer relationship among Adinandra, Cleyera, and Euryodendron on the one hand and between Eurya and Visnea on the other. Further, our developmental study stresses the differences between Pentaphylacaceae and Theaceae, which earlier where thought to form a natural group of plants. While high stamen numbers are achieved via centripetal pattern of stamen formation in the former family, stamens are formed centrifugally in the latter.     

Morphological studies in Zygophyllaceae. II. The floral development and vascular anatomy of Peganum harmala

Floral development and vascular anatomy are investigated in Peganum harmala, emphasizing its unusual androccium with 15 stamens. Sepals arise successively; petals emerge simultaneously with five antesepalous stamens. The five stamen pairs arise in the space between the petals and the antesepalous stamens. The gynoecium arises from three carpel primordia with evidence of two reduced carpels. Placentae are axile and each bears two double rows of ovules. A weakly developed nectary surrounds the base of the ovary. The antepetalous stamen traces diverge from a common supply to petals and sepal laterals, independent of the antesepalous stamen traces. The androecium of Peganum is described as a derived obdiploste-monous form, differing from the complex haplostemonous androecium of Nitraria. “Congenital dédoublement” cannot adequately explain the origin of the paired antepetalous stamens; two stamens can arise either by the splitting of a common primordium or independently, and both ways of inception are best understood as extremes of a gradation. The systematic position of Peganum is discussed in relation to other Zygophyllaceae using a cladistic analysis with Ptelea (Rutaceae) and Quassia (Simaroubaceae) as outgroups. The basal division in the Zygophyllaceae is between Peganum and the rest of the family.     

Effects of Infestation by the Balsam Woolly Aphid, Adelges Piceae (Ratz.) on the Ultrastructure of Bodered-Pit Membranes of Grand Fir, Abies grandis (Doug.) Lindl.

The ultrastructure of bordered-pit membranes in normal grandfir trees, Abies grandis (Doug.) Lindl., was compared with thatin trees infested with the blasam woolly aphid, Adelges piceae(Ratz). In sapwood of non-infested trees the membranes of earlywoodpits were well perforated, whereas those of latewood pits wereeither heavily incrusted or incompletely developed and showedfew perforations. In the heartwood pit membranes from both earlywoodand latewood were heavily incrusted. In aphid-infested trees all the pit membranes from the sapwoodwere incrusted and resembled those from heartwood of non-infestedtrees. These incurstations reduced the number of pores in themargo of pit membranes, and could account for the reduced permeabilityto water reported for sapwood trees attacked by the aphid. Wesuggest that the incrustation of pit membranes in sapwood inAbies grandis infested with Adelges piceae occurs because theseaphids cause heartwood to form prematurely.     

漠甲亚科八种幼虫记述(鞘翊目：拟步甲科)

漠甲亚科Pimcliinae是一类广布于古北区的耐旱沙漠昆虫,幼虫在沙土内发育,危害 植物嫩芽和根部,经济意义较大。本文记述了采自宁夏、甘肃、内蒙古和新疆的8个种,即多毛扁漠甲、谢氏宽漠甲、泥脊漠甲^[1]、洛氏脊漠甲^[1]、光滑胖漠甲^[1]、蒙古漠王、谢氏宽漠王和大宽漠王的幼虫,并给出它们的检索表。幼虫标本保存于宁夏农学院。     

Floral ontogeny of Ruteae (Rutaceae) and its systematic implications

Floral development was investigated in Ruta graveolens and Psilopeganum sinense, representing two genera in the tribe Ruteae. Special attention was paid to the sequence of initiation of organ whorls in the androecium and gynoecium. The antepetalous stamens arise at the same level as the antesepalous stamens in both species. The carpels are antepetalous in both taxa, indicating the androecium in both genera is obdiplostemonous. Compared with floral ontogeny of the ancestral genus Phellodendron (Toddalioideae), the obdiplostemonous androecium is a derived condition. The floral apex in P. sinense is quadrangular before initiation of the two carpels. Additionally, there are four dorsal and four ventral traces in the ovary. Integrated morphological and anatomical evidence indicates that the bicarpellate gynoecium in Psilopeganum most likely evolved from a tetracarpellate ancestor. Considering the similarities in morphological, geographical and chromosomal features, the ancestor may be Ruta‐like. Further molecular phylogenetic and genetic studies are needed to verify this assumption.     

Fossil flowers and fruits of the Actinidiaceae from the Campanian (Late Cretaceous) of Georgia

A new genus and species of Actinidiaceae (Parasaurauia allonensis gen. et sp. nov.) are established for fossil flowers and fruits from the early Campanian (Late Cretaceous) Buffalo Creek Member of the Gaillard Formation in central Georgia, USA. The fossil flowers, which are exquisitely preserved as charcoal, have five imbricate, quincuncially arranged sepals and petals. The androecium consists of ten stamens with anthers that are deeply sagittate proximally. The gynoecium is tricarpellate, syncarpous, and has three free styles that emerge from an apical depression in the ovary. The fruit is trilocular and contains numerous ovules on intruded axile placentae. The structure of mature fruits is unknown. Comparisons with extant taxa clearly demonstrate that the affinities of Parasaurauia allonensis are with the Ericales, and particularly with the Actinidiaceae, which have been placed among the Ericales in recent cladistic analyses. Because Parasaurauia allonensis is not identical to any one genus of Actinidiaceae, or other member of the Ericales, phylogenetic relationships of the fossil were evaluated through a cladistic analysis using morphological and anatomical characters. Results of this analysis place Parasaurauia allonensis within the Actinidiaceae as sister to the extant genera Saurauia and Actinidia. Parasaurauia allonensis differs from extant Saurauia only in having ten rather than numerous stamens.     

The impact of receptacular growth on polyandry in the Myrtales

RONSE DECRAENE, L.-P. & SMETS, E., 1991. The impact of receptacular growth on polyandry in the Myrtales. The androecium of the Myrtales shows a wide variation in structure and development, linked with an original diplostemony. The difference between a centrifugal stamen inception in Lythraceae against a centripetal inception in other families has been a major issue in discussing the internal relationships of the Myrtales. The first stamens usually arise as pairs opposite the petals on primary androecial primordia. It is shown that the number of stamens that are initiated and the difference between the direction of development of more stamens are based on the extent of growth of the receptacle after the inception of the primary androecial primordia. In Lagerstroemia indica , receptacular growth takes place between stamens and petals providing room for a centrifugal development. In the Punicaceae and Myrtaceae growth of the receptacle occurs between the androecium and gynoecium, leading to a centripetal development of the stamens. The development of a ring-wall is discussed and a comparison is made with other types of complex polyandry.