Fertile Carpel Research Articles

Evolutionary history of the grass gynoecium.

The grass family (Poaceae) includes cereal crops that provide a key food source for the human population. The food industry uses the starch deposited in the cereal grain, which develops directly from the gynoecium. Morphological interpretation of the grass gynoecium remains controversial. We re-examine earlier hypotheses and studies of morphology and development in the context of more recent analyses of grass phylogenetics and developmental genetics. Taken in isolation, data on gynoecium development in bistigmatic grasses do not contradict its interpretation as a solitary ascidiate carpel. Nevertheless, in the context of other data, this interpretation is untenable. Broad comparative analysis in a modern phylogenetic context clearly demonstrates that the grass gynoecium is pseudomonomerous. A bistigmatic grass gynoecium has two sterile carpels, each producing a stigma, and a fertile carpel that lacks a stigma. To date, studies of grass developmental genetics and developmental morphology have failed to fully demonstrate the composite nature of the grass gynoecium be-cause its complex evolutionary history is hidden by extreme organ integration. It is problematic to interpret the gynoecium of grasses in terms of normal angiosperm gynoecium typology. Even the concept of a carpel becomes misleading in grasses; instead, we recommend the term pistil for descriptive purposes.

Refined Interpretation of the Pistillate Flower in Ceratophyllum Sheds Fresh Light on Gynoecium Evolution in Angiosperms.

Molecular phylogenetic analyses have revealed a superclade of mesangiosperms with five extant lineages: monocots, eudicots, magnoliids, Ceratophyllum and Chloranthaceae. Both Ceratophyllum and Chloranthaceae are ancient lineages with a long fossil record; their precise placement within mesangiosperms is uncertain. Morphological studies have suggested that they form a clade together with some Cretaceous fossils, including Canrightia, Montsechia and Pseudoasterophyllites. Apart from Canrightia, members of this clade share unilocular gynoecia commonly interpreted as monomerous with ascidiate carpels. Alternatively, the gynoecium of Ceratophyllum has also been interpreted as syncarpous with a single fertile carpel (pseudomonomerous). We investigate patterns of morphological, anatomical and developmental variation in gynoecia of three Ceratophyllum species to explore the controversial interpretation of its gynoecium as either monomerous or pseudomonomerous. We use an angiosperm-wide morphological data set and contrasting tree topologies to estimate the ancestral gynoecium type in both Ceratophyllum and mesangiosperms. Gynoecia of all three Ceratophyllum species possess a small (sometimes vestigial) glandular appendage on the abaxial side and an occasionally bifurcating apex. The ovary is usually unilocular with two procambium strands, but sometimes bilocular and/or with three strands in C. demersum. None of the possible phylogenetic placements strongly suggest apocarpy in the stem lineage of Ceratophyllum. Rescoring Ceratophyllum as having two united carpels affects broader-scale reconstructions of the ancestral gynoecium in mesangiosperms. Our interpretation of the glandular appendage as a tepal or staminode homologue makes the Ceratophyllum ovary inferior, thus resembling (semi)inferior ovaries of most Chloranthaceae and potentially related fossils Canrightia and Zlatkocarpus. The entire structure of the flower of Ceratophyllum suggests strong reduction following a long and complex evolutionary history. The widely accepted notion that apocarpy is ancestral in mesangiosperms (and angiosperms) lacks robust support, regardless of which modes of carpel fusion are considered. Our study highlights the crucial importance of incorporating fossils into large-scale analyses to understand character evolution.

Flower structure and development in Pennantiaceae: uncovering diversity of pseudomonomerous gynoecia in the basal grade of the order Apiales

Abstract Pseudomonomerous gynoecia with three (or four) carpels are unknown in the species-rich core group of Apiales, but this condition is shared by three species-poor families (Pennantiaceae, Torricelliaceae, Griseliniaceae) that form the basal grade of the order. Testing a hypothesis on the ancestral nature of carpel dimorphism in Apiales requires comparative data for all three lineages in this grade. We provide the first detailed description of flowers, including floral vasculature and gynoecium development, in a member of Pennantiaceae (Pennantia corymbosa). In contrast to many other Apiales, the inflorescence of Pennantia is paniculate and therefore has an unstable number of phyllomes in axes terminated by flowers. All phyllomes in the inflorescence are shifted onto lateral branches they subtend exhibiting recaulescence, a pattern that has not been reported elsewhere in Apiales. Plants are dioecious with functionally unisexual flowers. There are normally five stamens alternating with five petals. Anthers are present and produce pollen in stamens of male as well as female flowers, but ventral microsporangia are reduced in some anthers of female flowers. Anther morphology sometimes varies even among stamens of the same flower. Two types of synthecal anthers are recorded. Pollen dimorphism is confirmed: inaperturate pollen produced by stamens of female flowers supposedly acts as the only reward for pollinators in the absence of nectaries. The gynoecium of the female flower is syncarpous and pseudomonomerous: only one of three carpels is fertile. The gynoecium is initiated as three carpel primordia (future stigmas). One of them is smaller than the other two and occupies an alternistaminal (and antepetalous) position. The two large carpel primordia are located in the radii of stamens that are generally smaller (early in development) than the three other stamens. The carpel dimorphism is maintained at anthesis. The carpel with the smaller stigma is fertile, and those with larger stigmas are sterile. The carpels are congenitally united below the stigmas. The ovary is superior, unilocular (vs. inferior and plurilocular in Torricelliaceae and Griseliniaceae) and usually uniovulate with pendent ovule(s) inserted at the cross-zone level of the fertile carpel. As in most other Apiales, the short symplicate zone is sealed by postgenital fusion at anthesis and forms an internal compitum. The fertile carpel of the members of the basal grade of Apiales investigated so far is uniformly arranged in a petal radius. This is consistent with the idea that pseudomonomery is associated with stable patterns of flower groundplan in Apiales. Our data do not provide any clear structural or developmental evidence of independent origins of carpel dimorphism in Pennantiaceae, Torricelliaceae and Griseliniaceae.

Correlations between gynoecium morphology and ovary position in angiosperm flowers: Roles of developmental and terminological constraints

The angiosperm gynoecium consists of elementary units called carpels. These can be free (apocarpy) or united (coenocarpy, or syncarpy in a wide sense). One of the most complicated problems of evolutionary morphology of angiosperms is distinguishing monomerous and pseudomonomerous gynoecia. The former are assumed to be derived by the reduction of the carpel number in apocarpous gynoecia, and the latter are assumed to be derived by reduction of gynoecia with united carpels. Pseudomonomerous gynoecia have one fertile carpel and more or less prominent traces of sterile carpel(s). In extreme cases of reduction, pseudomonomerous gynoecia are very similar to monomerous, even though the two types have completely different evolutionary histories. G.B. Kedrov (1969) proposed a new approach to resolve the issue. Using the absence of polymerous free-carpellate gynoecia with inferior ovaries, he suggested that there is a constraint for epigyny in plants with free carpels. Therefore, in taxa with disputable morphological interpretations, the gynoecium should be treated as pseudomonomerous (and not monomerous) if the ovary is inferior. A critical review of the concept of G.B. Kedrov showed that his ideas would suggest reinterpretation of widely accepted views on gynoecium morphology in several key families of basal angiosperms. An alternative view is proposed: for the most important types of epigyny in angiosperms, the “constraint” for the combination of inferior ovary and apocarpy is due to the definition of the term “apocarpy” only. There is no biological sense in this “constraint.” The existence of two other morphogenetic constraints is proposed: (1) on the presence of a typical inferior ovary in monomerous gynoecia with conduplicate carpel and (2) on the radial (sectorial) fusion of individual carpels with stamens or perianth members without fusion of these groups into an entire structure. The possible biological nature of these constraints is discussed.

Floral structure of Emmotum (Icacinaceae sensu stricto or Emmotaceae), a phylogenetically isolated genus of lamiids with a unique pseudotrimerous gynoecium, bitegmic ovules and monosporangiate thecae.

Icacinaceae sensu stricto consist of a group of early branching lineages of lamiids whose relationships are not yet resolved and whose detailed floral morphology is poorly known. The most bizarre flowers occur in Emmotum: the gynoecium has three locules on one side and none on the other. It has been interpreted as consisting of three fertile and two sterile carpels or of one fertile carpel with two longitudinal septa and two sterile carpels. This study focused primarily on the outer and inner morphology of the gynoecium to resolve its disputed structure, and ovule structure was also studied. In addition, the perianth and androecium were investigated. Flowers and floral buds of two Emmotum species, E. harleyi and E. nitens, were collected and fixed in the field, and then studied by scanning electron microscopy. Microtome section series were used to reconstruct their morphology. The gynoecium in Emmotum was confirmed as pentamerous, consisting of three fertile and two sterile carpels. Each of the three locules behaves as the single locule in other Icacinaceae, with the placenta of the two ovules being identical, which shows that three fertile carpels are present. In addition, it was found that the ovules are bitegmic, which is almost unique in lamiids, and that the stamens have monosporangiate thecae, which also occurs in the closely related family Oncothecaceae, but is not known from any other Icacinaceae sensu lato so far. The flowers of Emmotum have unique characters at different evolutionary levels: the pseudotrimerous gynoecium at angiosperm level, the bitegmic ovules at lamiid level and the monosporangiate thecae at family or family group level. However, in general, the floral morphology of Emmotum fits well in Icacinaceae. More comparative research on flower structure is necessary in Icacinaceae and other early branching lineages of lamiids to better understand the initial evolution of this large lineage of asterids.

Comparative floral morphology and anatomy of Anacardiaceae and Burseraceae (Sapindales), with a special focus on gynoecium structure and evolution

Anacardiaceae and Burseraceae are traditionally distinguished by the number of ovules (1 vs. 2) per locule and the direction of ovule curvature (syntropous vs. antitropous). Recent molecular phylogenetic studies have shown that these families are sister groups in Sapindales after having been separated in different orders for a long time. We present a comparative morphological study of the flower structure in both families. The major clades, usually supported in molecular phylogenetic analyses, are well supported by floral structure. In Anacardiaceae, there is a tendency to gynoecium reduction to a single fertile carpel (particularly in Anacardioideae). The single ovule has a long and unusually differentiated funicle, which connects with the stylar pollen tube transmitting tract in all representatives studied. In Anacardiaceae–Spondiadoideae, there is a tendency to form an extensive synascidiate zone, with a massive remnant of the floral apex in the centre; these features are also present in Beiselia (Burseraceae) and Kirkiaceae (sister to Anacardiaceae plus Burseraceae) and may represent a synapomorphy or apomorphic tendency for the three families. In core Burseraceae, gynoecium structure is much less diverse than in Anacardiaceae and has probably retained more plesiomorphies. Differences in proportions of parts of the ovules in Anacardiaceae and Burseraceae are linked with the different direction of ovule curvature. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159, 499–571.

The S locus‐linked Primula homeotic mutant sepaloid shows characteristics of a B‐function mutant but does not result from mutation in a B‐function gene

Floral homeotic and flower development mutants of Primula, including double, Hose in Hose, Jack in the Green and Split Perianth, have been cultivated since the late 1500s as ornamental plants but until recently have attracted limited scientific attention. Here we describe the characterization of a new mutant phenotype, sepaloid, that produces flowers comprising only sepals and carpels. The sepaloid mutation is recessive, and is linked to the S locus that controls floral heteromorphy. The phenotype shows developmental variability, with flowers containing three whorls of sepals surrounding fertile carpels, two whorls of sepals with a diminished third whorl of sepals surrounding a fourth whorl of carpels, or three whorls of sepals surrounding abnormal carpels. In some respects, these phenotypes resemble the Arabidopsis and Antirrhinum homeotic B-function mutants apetala3/deficiens (ap3/def) and pistillata/globosa (pi/glo). We have isolated the Primula vulgaris B-function genes PvDEFICIENS (PvDEF) and PvGLOBOSA (PvGLO), expression of both of which is affected in the sepaloid mutant. PvGLO, like sepaloid, is linked to the S locus, whereas PvDEF is not. However, our analyses reveal that sepaloid and PvGLO represent different genes. We conclude that SEPALOID is an S-linked independent regulator of floral organ identity genes including PvDEF and PvGLO.

Anatomical studies on Sinofranchetia chinensis (Lardizabalaceae) and their systematic significance

The anatomical structures of the Chinese endemic and monotypic genus Sinofranchetia (Lardizabalaceae) are described. There are reticulate, simple-reticulate, scalariform, simple-scalariform and simple perforations in vessel elements as well as in the fibres in the secondary wood of the roots and the stems. The node is trilacunar. The vascular bundles in the petiole are arranged in a ring. Clustered crystals occur in the parenchymatous cells of stems, petioles and pedicles. Leaf stomata are actinocytic. The nodes of sepals, petals and stamens both in male and female flowers are unilacunar and one-traced. There are three sterile carpels with two to three traces in the male flowers, three fertile carpels with two to three traces, and sometimes three sterile carpels lacking a vascular supply. In morphology, the anther dehiscence mechanism and pollen in the female flowers are the same as in the male flowers, such that the so-called female flowers might be bisexual in morphology. In comparing morphology, the sex of the flowers and the perforations of the vessel elements in Sinofranchetia with Decaisnea and other genera of the Lardizabalaceae, Sinofranchetia is considered a basic group at least as the same evolutionary level in the family as Decaisnea. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 149, 271–281.

Comparative floral anatomy of Pontederiaceae

Floral anatomy is described in eight species (representing five genera) of Pontederiaceae, and floral ontogeny is described in Pontederia cordata. The results are assessed in the context of recent phylogenetic work on Pontederiaceae, which indicates that the unilocular ovary condition has been achieved by two different, non-homologous routes in Pontederiaceae: via loss of interlocular septa in Heteranthera and Hydrothrix, and via pseudomonomery in Pontederia, which has a single fertile carpel. Absence of septal nectaries has evolved more than once in Pontederiaceae, at least in Heterantha and Monochoria, probably due to a transfer of the insect reward from nectar to pollen in these taxa. The presence of an elliptical or linear unvascularized appendage on the abaxial outer stamen in Monochoria is also probably correlated with enantiostyly. In Pontederia, air spaces in the ovary wall are modified into canals, each with a ring of apparently secretory epithelial cells. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144, 395–408.

Floral anatomy in Dypsis (Arecaceae–Areceae): a case of complex synorganization and stamen reduction

Male (staminate) flowers of Dypsis possess either six or three stamens and/or staminodes, in contrast to most other palms, in which the basic stamen number is six (although polyandry is also common in palms). Significant variation among the tristaminate forms, both in stamen morphology and stamen position with respect to the perianth parts, indicates that stamen reduction from six to three has occurred more than once, and possibly several times within Dypsis. A few species include teratological forms with zygomorphic flowers; for example, Dypsis lantzeana normally possesses three antesepalous stamens, but in some specimens only the median outer (abaxial) stamen is expressed, perhaps indicating incipient zygomorphy correlated with complex synorganization. Inclusion of earlier historic genera such as Neophloga and Chrysalidocarpus within a broadly circumscribed Dypsis appears to be justified, although the informal taxonomic groupings within Dypsis require review, in particular the taxonomic significance of the different types of anther morphology. The discovery here that adnation of staminodes to the pistillode (complex synorganization) occurs in species other than D. mirabilis opens further questions about the taxonomic utility of this character in Dypsis, in which stamen/staminode development and adnation are apparently unusually labile. Such androecial–gynoecial adnation is otherwise rare in palms, as also in other monocots, in which probably the best-known example occurs in orchids. Septal nectaries are present in some, but not all, staminate flowers in species of Dypsis. Dypsis bejofo is exceptional in that in staminate flowers the pistillode is distally bulbous and bears three prominent modified supralocular septal nectaries. Female (pistillate) flowers in Dypsis are syncarpous, normally pseudomonomerous (as in many other Arecoideae), and possess septal nectaries that effectively delimit the carpel margins and indicate insect pollination. There is a central solid transmitting tissue that extends from the placenta to three stylar canals. The stylar canals of the two sterile carpels are apparently functional, in addition to that of the fertile carpel. © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 143, 115−133.

Morphology and development of the female flowers in Geonoma interrupta (Arecaceae)

Morphology and development of the female flowers in Geonoma interrupta are described and compared with other taxa within Arecaceae. Inflorescences are pleiothyrses. Cincinni are immersed in pits and arranged according to the Fibonacci pattern along the rachillae. The gynoecium is composed of three free carpels in early stages and later becomes pseudomonomerous. Two carpels are sterile; they develop to different degrees and are commonly unequal in size. The fertile carpel contains a single, crassinucellate, anatropous ovule. Styles are formed in each carpel. The style of the fertile carpel becomes basifixed as the ovary enlarges. The stigmas remain free and plicate during development and expose unicellular papillae at anthesis. Pollen tube transmitting tracts and a compitum are present in the ventral slits of the stigmas and the postgenitally united styles during anthesis. A septal nectary is formed by incomplete union of the flanks of the carpels at the base of the gynoecium, and nectar is secreted from an epithelium. It is suggested that in Geonoma as a whole, the attraction of pollinators to female flowers is due to a combination of nectar reward and partial mimicry of male flowers.

Male and female flowers of the dioecious plant sorrel show different patterns of MADS box gene expression.

Male and female flowers of the dioecious plant sorrel (Rumex acetosa) each produce three whorls of developed floral organs: two similar whorls of three perianth segments and either six stamens (in the male) or a gynoecium consisting of a fertile carpel and two sterile carpels (in the female). In the developing male flower, there is no significant proliferation of cells in the center of the flower, in the position normally occupied by the carpels of a hermaphrodite plant. In the female flower, small stamen primordia are formed. To determine whether the organ differences are associated with differences in the expression of organ identity genes, cDNA clones representing the putative homologs of B and C function MADS box genes were isolated and used in an in situ hybridization analysis. The expression of RAD1 and RAD2 (two different DEFICIENS homologs) in males and females was confined to the stamen whorl; the lack of expression in the second, inner perianth whorl correlated with the sepaloid nature of the inner whorl of perianth segments. Expression of RAP1 (a PLENA homolog) occurred in the carpel and stamen whorls in very young flower primordia from both males and females. However, as soon as the inappropriate set of organs ceased to develop, RAP1 expression became undetectable in those organs. The absence of expression of RAP1 may be the cause of the arrest in organ development or may be a consequence.

A Revision of Dicella (Malpighiaceae)

Placement of the South American genus Dicella Grisebach (Malpigh- iaceae), which contains six species, is discussed, as well as the salient morphological features employed in its taxonomy. A key is provided to the two sections and the six species. All taxa are described, including, for the first time, Dicella oliveirae and sect. Macropterys. Dicella was established by Grisebach in 1839, based on D. bracteosa, which Adrien de Jussieu had originally described in 1832 as Bunchosia bracteosa. Both Grisebach and Jussieu realized that Bunchosia sensu Adr. Jussieu and Bunchosia sensu Rich. ex H.B.K. were not the same, and Grisebach erected Dicella to accommodate B. bracteosa. Dicella is readily distinguished from other Malpighiaceous genera by the combination of vining habit, decussate arrangement of decompound panicles with prominent, clasping bracts and bracteoles, densely pubes- cent petals, indehiscent nutlike fruits formed from fusion of one sterile and two fertile carpels, and expanded, persistent, winglike sepals of ma- ture fruits. Within the Malpighiaceae, Dicella stands in a rather isolated position. Niedenzu (1928) placed it in subfamily Planitorae, which he character- ized by having a flat torus and unwinged fruits. Genera with a pyramidal torus and winged fruits Niedenzu placed in his other subfamily, Pyr- amidotorae. In order to make this arrangement conform to the Code of Botanical Nomenclature, Morton (1968) proposed the epithets Malpigh- ioideae and Gaudichaudioideae, respectively. This arrangement of the Malpighiaceae is highly unnatural, however, especially for the Malpigh- ioideae. Anderson (1977) removed most of the genera from the Malpighioi- deae, naming his segregate subfamily Byrsonimoideae. The remainder, which includes Dicella, Malpighia, Bunchosia, and several other genera, is a rather heterogeneous group. Dicella certainly does not belong in the Byrsonimoideae and is probably more closely related to members of the Gaudichaudioideae (which will become the Malpighioideae if Malpighia is closely allied with Mascagnia, as Anderson believes). Other than its vining habit, however, Dicella does not share a significant number of features with any genus in the Gaudichaudioideae sensu Morton. Chromosome counts might aid in placement of the genus. Anderson (unpublished) found D. bracteosa to have n = 10. This count is consistent with the placement of Dicella near the vining genera within the Gaudi- chaudioideae, most of which have counts of n = 10 or multiples thereof

Stamen-carpel Homologies

The study of intermediate phyllomes (stamen-carpels) in Salix as well as the reassessment of previous observations lead the author to put forward a general interpretation of homologies between stamen and carpel. The stamen is considered diplophyllous, i.e. with two tangential blades topping an unifacial filament. The four margins of these blades form the four pollen sacs. If the filament were hollow instead of solid, there would arise a congenitally closed cavity as in a peltate carpel. Its back part would bear the posterior blade of the diplophyllous anther, its front portion the anterior blade. The latter is made up of two congenitally fused anterior lobes, one on each side of the fusion line, prolonging the corresponding line of the filament. When the upper parts of the margins are no longer fused along this line in a peltate carpel the ventral split arises and in a diplophyllous stamen the two ventral lobes are freed, as seen in stamen-carpels of Tulipa. When such a process occurs together with disappearance of pollen sacs, ovule formation on the ventral split and merging of the ventral lobes in the posterior (main) blade, a carpel arises whose blade incorporates both posterior and anterior blades of the corresponding stamen (Tofieldia type, Guédès 1965a). When the anterior blade disappears, the posterior blade alone gives birth to the carpellary blade (Sempervium type, also found in Tulipa). In Veronica, Papaver and Salix, the anterior blade proper fades out too, but intermediate appendages arise between its constituting anterior lobes and the posterior blade. The placental appendages fuse with the posterior blade and develop the ovules. Since when the posterior blade of Sempervivum or Tulipa forms such ovules, narrow strips are also added to it distally, the first-mentioned genera must be referred to the Sempervivum type as well. In all these instances, anther and filament may or may not take part in the formation of the fertile carpel portion. The issuing carpel is peltate or depending on to whether or not its blade margins are fused congenitally in their lower part. In teratologically isolated carpels of Salix replacing stamens, the margins are congenitally fused up to the apex with some ovules being borne only basally, and this affords a clue to the interpretation of normal carpels in Typha, the Potamogetonaceae, the Bignoniaceae and the Caryophyllaceae. As far as possible, an ontogenetical interpretation of these phenomena is set forth, taking account of modern views (Dulieu, Guédès) on foliage leaf ontogeny.

FLORAL ANATOMY OF KRAMERIA LANCEOLATA

The anatomy of each of the series of floral organs of Krameria lanceolata was examined. The sepals are characterized by three main veins each, an undifferentiated mesophyll, and stomata on the upper epidermis. The fleshy petals are distinguished by their numerous veins as well as by palisade‐like epidermal cells on the outer surface. The three partially united petals have each a single vein and long, narrow epidermal cells similar to those on other floral organs. The stamens are united at their bases and bear tetra‐sporangiate, conical anthers. The gynoecium includes a sterile and a fertile carpel. In the receptacle the veins to the sepals and petals are separated by a wide gap; those to the petals and stamens, by a narrow gap. Anatomical characteristics of the flower dissociate Krameriaceae from the legumes with which they have frequently been thought to be allied.

Floral Anatomy of Krameria lanceolata

The anatomy of each of the series of floral organs of Krameria lanceolata was examined. The sepals are characterized by three main veins each, an undifferentiated mesophyll, and stomata on the upper epidermis. The fleshy petals are distinguished by their numerous veins as well as by palisade-like epidermal cells on the outer surface. The three partially united petals have each a single vein and long, narrow epidermal cells similar to those on other floral organs. The stamens are united at their bases and bear tetra-sporangiate, conical anthers. The gynoecium includes a sterile and a fertile carpel. In the receptacle the veins to the sepals and petals are separated by a wide gap; those to the petals and stamens, by a narrow gap. Anatomical characteristics of the flower dissociate Krameriaceae from the legumes with which they have frequently been thought to be allied.

Studies of Floral Morphology in the Epacridaceae

1. The organography and vascular anatomy of the flower have been described for twenty-four species representing twelve genera of the Epacridaceae: in the Epacrideae, Dracophyllum secundum, Epacris impressa, E. longiflora, E. pulchella, Sprengelia incarnata, and S. ponceletia; and in the Styphelieae, Acrotriche aggregata, A. depressa, A. serrulata, Astroloma conostephioides, Brachyloma ericoides, Leucopogon amplexicaulis, L. attenuatus, L. biflorus, L. concurvus, L. melaleucoides, L. microphyllus, L. richei, Lissanthe strigosa, Melichrus procumbens, M. urceolatus, Monotoca scoparia, Styphelia triflora, and Trochocarpa laurina. 2. The flowers of the Epacridaceae are bracteate, tetracyclic, normally pentamerous, sympetalous, hypogynous, and actinomorphic. Anthers are introrse and appendaged only in some species of Leucopogon and in Melichrus. The fruit is either a loculicidal capsule (Epacrideae) or drupaceous (Styphelieae). The ovary is composed basically of five carpels, although the actual number of locules in the ovary ranges from one to ten. The axile placentae bear more than one ovule in the Epacrideae but only one in the Styphelieae. 3. The vascular tissue in the pedicel forms a complete cyclinder which is broken by single traces to the bracts and bracteoles. The cylinder may be continuous or broken at the level of divergence of the sepal traces. In acropetal succession whorls of traces to the following organs arise: sepals; petals; stamens; and dorsal, septal, and ventral regions of the carpels. Various degrees of non-divergence between traces occur, particular between stamen and septal carpel supply. In two species the ventral carpel bundles are found to differentiate and mature basipetally in the central column. 4. Traces to the sepals are occasionally three but more often one; when three, the lateral traces may be independent or arise in common with the adjacent petal traces. The sepal traces may branch immediately on leaving the central cylinder or only in the base of the calyx. The vascular bundles in the sepals are usually associated with either a continuous band or groups of fibers. 5. In the Styphelieae there may be fertile and sterile carpels in the same whorl. The dorsal carpel bundles of the fertile carpels and sometimes of the sterile carpels extend into the style; the laterals and septals fade at the summit of the ovary. 6. The anatropous ovules are unitegmic and tenuinucellate and have a well-developed endothelium. The eight-nucleate megagameotphyte arises from a single archesporial cell. Either the micropylar (6, 33) or chalazal megaspore of a linear tetrad functions; that is, development is of the Polygonum type. A filiform apparatus is frequently present in the synergids. 7. A comparison of the organography and vascular anatomy of the flowers supports the retention of the usual generic divisions in the Epacridaceae and the close affinity of this family with the Ericaceae.

CARPEL MORPHOLOGY IN THE CRUCIFERAE

In the investigation of the floral anatomy of the Cruciferae and some allied families, with the object of determining the fuindamental floral structure of the groups, the writers have obtained evidence which compels them to reopen a subject of long controversy-the nature of the ovary of the Cruciferae. Further, light is also shed upon the recently proposed theory of carpel polymorphism as applied to this family. The structure of the crucifer gynoecium hlas long been a subject of discussion, especially in regard to the number and type of carpels, and the nature of the septum, or false partition. Students of this subject have held several theories as to the nature of the ovary. Of these the chief are, (i) that the pistil consists of two carpels; (2) that there are four carpels, either in one whorl or in two whorls of two each. That the number of carpels is six has also been maintained; and recently as many as IO-20 have been considered to compose the pistil in some genera. The two-carpel theory seems to be commonly held today. Accordiulg to this understanding there are two open carpels fused edge to edge forming the ovary. The fused margins of these carpels bear the placentae, and outgrowths of the placentae divide the really one-celled ovary. The septum is thus false. Those students holding that there are four carpels lhave generally believed that two of these are reduced or aborted. In such cases the ovules are said to be borne on placenital surfaces (of which there are four), placed between the normal and the reduced carpels; and opinions have varied as to the carpel to which the ovules belong, and hence which type of carpel is sterile and which is fertile. A prominent theory, put forth and emphasized by older writers, and recently renewed, and supported with new facts by Miss Saunders (26), is that the so-called valves of the ovary make up the sterile carpels, the fertile carpels being composed of the segments between the valves. The relationship of these two types of carpels can be understood by reference to text figure I. Many supporters of this theory, as well as of the two-carpel theory, have considered the septum, or false partition, to be a secondary placental outgrowth. A few have considered this dissepiment to represent carpellary tissue of the fertile carpels. If the septum is truly carpellary, then it must represent either the venitral part of the carpel itself or a much expanded margin of the carpel. If the dissepiment is false, that is, of placental