Free Styles Research Articles

Pollen Tube Distribution in the Kiwifruit (Actinidia deliciosaA. Chev. C. F. Liang) Pistil in Relation to its Reproductive Process

High resolution light and fluorescence microscopy were used to investigate the structural and cytochemical features of the kiwifruit(Actinidia deliciosa)pistil and to follow the pollen tube pathway after pollination. The multicarpellary ovary is syncarpous only at the ovary level thus leaving 30–40 free styles on top. The fusion of the longitudinally-folded carpels to form the syncarpous ovary forms a central parenchymatous axis, the columella, from which the ovules radiate outwards into the ovary cavity. A prominent cup shaped depression on the columella at the top end of the ovary, termed the pollen tube distributor cup (PTDC) was detected. Pollen tubes from the stigma travel through the transmitting tract and enter the PTDC from where they are distributed towards the ovary. Even when pollination is restricted to two stigmas, the PTDC seems to ensure that the pollen tubes are evenly distributed around the ovary resulting in an even distribution of seeds. This suggested role of the PTDC which could compensate for over and under pollination of individual stigmatic arms is another adaptive feature which plays a crucial role in the reproductive process of kiwifruit. The significance of this structure for pollination by insects is discussed.

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.

A New Section and Two New Species of Tragia (Euphorbiaceae) from the Venezuelan Guayana and French Guiana

A New Section and Two New Species of Tragia (Euphorbiaceae) from the Venezuelan Guayana and French Guiana

A New Bonamia (Convolvulaceae) from Nicaragua

A new species of Bonamia has been discovered in the Department of Chontales in Nicaragua. Bonamia douglasii is described and compared with other large-sepaled species in the world. This species differs from the other Central and North American members of the genus in being a woody climber with two cordate outer sepals larger than the inner three. RESUMEN. Una especie nueva de Bonamia se ha descubierto en el Departamento de Chontales de Nicaragua. Bonamia douglasii se describe y se contrasta con las otras mundiales del genero con sepalos grandes. Esta especie se difiere de las demas de la America Central y Norte en que es una trepadora leiiosa con los dos sepalos exteriores mayores que los interiores. Myint & Ward (1968) recognized 23 neotropical species in Bonamia A. Thouars. Revision of the genus based on the more abundant material now available indicates that 18 of the species they studied should be retained (Austin & Staples, unpublished data). However, exploration in the American tropics since the early 1970s has resulted in the addition of B. apurensis D. F. Austin (1982a), B. mexicana J. A. McDonald (1987), and B. leonii A. H. Gentry & D. F. Austin (1988). During study of specimens for the Flora de Nicaragua, I encountered yet another Bonamia that previously had not been recognized. Because the specimen represents a unique, locally endemic taxon, it is presented as new. The following, along with the three species recently described, brings the current neotropical generic total to 22. Bonamia has recently been delimited by Verdcourt (1963, 1974), Myint & Ward (1968), Austin (1975, 1982a, b), Austin & Ghazanfar (1979), Austin & Cavalcante (1982), Austin & Staples (1985), Goncalves (1987), and Breteler (1992). In these studies the genus was delimited as having free or partially free styles, non-accrescent sepals, dehiscent fruits, and ovate, obovate, or ovate-cordate cotyledons. Bonamia douglasii D. F. Austin, sp. nov. TYPE: Nicaragua. Dept. Chontales: Hacienda Veracruz, 12011'N, 85?22'W, elev. 120-140 m, pastures and gallery forest, 19 Dec. 1984 (fls & buds), W. Douglas Stevens 23522 (holotype, MO; isotype, FAU). Figure 1. Species B. sulphureae affinis, sed ab ea sepalis exterioribus amplis reniformibus, sepalis interioribus minoribus differt. Perennial climbers, woody, the stems twining, appressed brown-sericeous when young, glabrescent, older stems brown, lenticellate, striate. Leaves simple, petiolate; lamina coriaceous, elliptic to broadly ovate, 2.5-5.8 cm long, 1.8-5 cm wide, entire, the apex obtuse to mucronate, apiculate, the base obtuse to rounded, brown-sericeous, 4-6 veins conspicuous below, obscure above; petiole canaliculate, 2-5 mm long, 2 mm wide, brown-sericeous. Inflorescences racemose to flowers solitary, near the ends of terminal or on lateral branches, peduncles reduced to ca. 2 mm on solitary flowers, 3-4 mm long in racemes, brown-sericeous; pedicels 5-8 mm long, brown-sericeous; bracts scalelike, 1.5 mm long, triangular, brown-sericeous; sepals unequal, imbricate, the outer longer and broader than the inner, reniform, 8-9 mm long, 9-12 mm wide, coriaceous, basally obtuse, apically rounded, the margins entire, undulate, brown-sericeous, the inner 6-7 mm long, 3-5 mm wide, chartaceous, glabrous; corolla induplicate-valvate and convolute, funnel-shaped, 1618 mm long, white, brown-sericeous on the midpetaline bands with V-shaped trichomes, the cylindrical tube 6-7 mm long, glabrous; the limb almost entire; stamens equal, included, 4-5 mm long, the filaments fused to the corolla tube, glabrous at the base, the anthers 1-1.5 mm long; nectary 5-lobed; ovary ovoid, 2.5 mm wide and long, brown-sericeous throughout most of the length, the trichomes V-shaped, some areas near the bottom glabrous, the styles 2, unequal, 5-7 mm long, the stigmas capitate, 1 mm wide. Fruits not seen. The epithet is dedicated to W. Douglas Stevens, indefatigable student of Nicaraguan botany. NOVON 4: 319-321. 1994. This content downloaded from 157.55.39.211 on Mon, 08 Aug 2016 06:05:50 UTC All use subject to http://about.jstor.org/terms

Archamamelis, hamamelidalean flowers from the Upper Cretaceous of Sweden

Lignite fossil flowers (including pollen) and isolated stamens of probable hamamelidalean (possible hamamelidaceous) affinities from the upper Cretaceous (Late Santonian or Early Campanian) of Sweden are described. The flowers are 6–7-merous with probably a double perianth, one whorl of stamens and (2-?)3 carpels. The stamens are disporangiate; each theca opens by a valve towards the centre of the flower. Pollen is tricolpate, tectate-columellate and reticulate; the endexine is lamellated in the apertural region. The gynoecium has free styles and a syncarpous ovary. In the one flower that was serially sectioned the ovary is either non-functional or development of the few (2?) ovules is retarded.

Floral Development of Hydrocharis morsus-ranae (Hydrocharitaceae)

In both male and female flowers of H. morsus-ranae the primordia of the floral appendages appear in an acropetal succession consisting of alternating trimerous whorls. In the male flower a whorl of sepals is followed by a whorl of petals, three whorls of stamens, and a whorl of filamentous staminodes. The mature androecial arrangement therefore consists of two antisepalous stamen whorls, an antipetalous whorl of stamens, and antipetalous staminodes. Shortly before anthesis, basal meristematic upgrowth between filaments of adjacent whorls produces paired stamens, joining Whorls 1 and 3, and Whorl 2 with the staminodial whorl. A central domelike structure develops between the closely appressed filaments of the inner stamen and staminodial whorl, giving the structure a lobed appearance. After petal inception in the female flower a whorl of antisepalous staminodes develop, each of which may bifurcate to form a pair of staminodes. During staminode development a girdling primordium arises by upgrowth at the periphery of the floral apex. The girdling primordium rapidly forms six gynoecial primordia, which then go on to produce six free styles with bifid stigmas. Intercalary meristem activity, below the point of floral appendage attachment, leads to the production of a syncarpous inferior ovary with six parietal placentae. The styles and carpels remain open along their ventral sutures. During the final stages of female floral development, several hundred ovules develop along the carpel walls, and three nectaries develop dorsally and basally on the three antipetalous styles.

FLORAL DEVELOPMENT OF HYDROCHARIS MORSUS‐RANAE (HYDROCHARITACEAE)

In both male and female flowers of H. morsus‐ranae the primordia of the floral appendages appear in an acropetal succession consisting of alternating trimerous whorls. In the male flower a whorl of sepals is followed by a whorl of petals, three whorls of stamens, and a whorl of filamentous staminodes. The mature androecial arrangement therefore consists of two antisepalous stamen whorls, an antipetalous whorl of stamens, and antipetalous staminodes. Shortly before anthesis, basal meristematic upgrowth between filaments of adjacent whorls produces paired stamens, joining Whorls 1 and 3, and Whorl 2 with the staminodial whorl. A central domelike structure develops between the closely appressed filaments of the inner stamen and staminodial whorl, giving the structure a lobed appearance. After petal inception in the female flower a whorl of antisepalous staminodes develop, each of which may bifurcate to form a pair of staminodes. During staminode development a girdling primordium arises by upgrowth at the periphery of the floral apex. The girdling primordium rapidly forms six gynoecial primordia, which then go on to produce six free styles with bifid stigmas. Intercalary meristem activity, below the point of floral appendage attachment, leads to the production of a syncarpous inferior ovary with six parietal placentae. The styles and carpels remain open along their ventral sutures. During the final stages of female floral development, several hundred ovules develop along the carpel walls, and three nectaries develop dorsally and basally on the three antipetalous styles.

Cretaceous flowers from Kazakhstan

Hyrcantha gen. nov. from the Middle Albian is a paniculate inflorescence. The flowers are bisexual with persistent calyx and apocarpous gynoecium. The carpels are ascidial with broad sessile stigma. The genus is related to the Ranunculaceae and Paeoniaceae. The Late Cretaceous Sarysua gen. nov. has cymoid inflorescences of many actinomorphic pentamerous flowers with syncarpous five-lobed ovaries and free styles. A geranialean affinity is suggested. In Taldysaja of the same age much reduced pistillate flowers are born in spikelets or solitary on branches of the fasciculate inflorescence. These findings evidence the important role to be of the ranunculoid—paeonioid complex among ancestral angiosperm and the considerable diversity of the Late Cretaceous flowering structures.

A new species of Cordia (Boraginaceae) from Tanzania

Cordia fissistyla Vollesen is described. The species is endemic in SE Tanzania. It differs from all hitherto described species in having free styles.

Comparative morphology of the carpel in the Liliaceae: Baeometra, Burchardia and Walleria

The pistils in Baeometra, Burchardia and Walleria ate tricarpellate, and their ovules are mostly bitegmic. Baeometra has free styles and deep septal invaginations between the carpels. Its pistil is innervated by three dorsal bundles, three compound septal bundles (each of which may divide into two simple septal bundles above), six placental bundles, and six adjoining auxiliary placental bundles. The pistil of Burchardia resembles that of Baeometra, except that there are six simple septal bundles throughout and no auxiliary placental bundles. In Walleria the wings of adjoining carpels are completely fused (except for rare septal glands); there is a single compound style; additional vascular tissue is present in the central axis of the pistil up to the lowermost ovules; the carpels are fused with the floral cup above the base of the locules; and raphide idioblasts are present. Walleria has six “ventral” bundles, each of which appears to be the fusion product of a placental bundle with a simple septal bundle. Tribal affinities of these genera are discussed.

Contributions to the Flora of Tropical America: LXIX. A New Genus of Peridiscaceae

Peridiscus lucidus Benth. was first found by Spruce on the Rios Uaupes and Pacimoni and was recently collected near Manaus ( on the Rio Tarumi) by the late Dr. A. Ducke. Originally described by Bentham (1862) in the 'Genera Plantarum', it was figured with a fresh description by D. Oliver (1896) in Hooker's 'Icones Plantarum'. These authors both placed it, with some doubt, in the Bixaceae and it was maintained in that family by Eichler (1871) in Martius's 'Flora Brasiliensis', and at the end of the Flacourtiaceae, with doubt, by Dr. O. Warburg (1893) and E. Gilg (1925) in the first and second editions of the 'Pflanzenfamilien'. Recently, however, the plant has been studied afresh from Ducke's much better material, by Dr. J. G. Kuhlmann (I950). This author, who was apparently ignorant of Oliver's figure and description, after pointing out errors in the descriptions of Bentham, Eichler, Warburg and Gilg, rejected Peridiscus, not only from the Flacourtiaceae, but also from the Olacaceae and, finally, the Capparidaceae, in which latter family it had been placed by H. Hallier (I908). He proceeded to treat it as constituting a new family Peridiscaceae, the salient characters being the presence of stipules, apetaly, imbricate sepals, numerous stamens with monothecous anthers, a conspicuous disk surrounding the unilocular ovary, pendulous ovules from its apex, 3-4 free styles, a large, solitary seed with abundant horny endosperm, and a minute, straight embryo placed laterally in a shallow cavity near its apex. The characters of the endosperm and the embryo, he noted, are found in the Santalales. The family Peridiscaceae is accepted by Dr. J. Hutchinson (I959) in the new edition of his 'Families of Flowering Plants', and is placed in the Tiliales, 'for want of a better place', but he seems not to have read Kuhlmann's emended description and comments, for he repeats the errors of his predecessors, describing the sepals as valvate, the anthers (also figured) as 2-locular and the seed as without endosperm. Some of these characters could have been verified by examination of Ducke's specimens of Peridiscus lucidus at Kew. Again, it must be stated that the Peridiscaceae appears in Hutchinson's great 'Key to the Families' in a section with exstipulate leaves on p. 91, under Group 12, although he rightly mentions the stipules in his description of the family. The Potaro Valley material lacks fruits and seeds, but shows nearly all

Notes from the East African Herbarium: X

Mention should perhaps be made of a remarkable plant collected by Mr. O. West in Ethiopia during the 1939-45 war. The material is inadequate for description but was collected under difficulties. It is of interest from an evolutionary point of view. The outer sepals are united into an entire disc. The two inner sepals are minute. There are five filaments and two free styles with hippocrepiform stigmas. Every effort should be made to collect adequate material of this plant. Mr. C. F. Hemming has made an intensive search for it but he failed to find it.