Inferior Ovary Research Articles

The delimitation, infrageneric subdivision, ecology and distribution of BomareaMirbel (Alstroemeriaceae)

AbstractThe genus Bomarea (Alstroemeriaceae) was revised for the last time by Baker (1888). Since then the number of validly published names has increased from 75 to recently 280. A revision is urgently needed. Extended field studies in Peru (A. H.) revealed the experience to start this project. In the present paper the taxonomic history of the genus is described and the delimitation of Bomarea to the closely related genus Alstroemeria is analysed. Among the most important differences between the two genera are the fruit structure and the basic chromosome numbers, in Alstroemeria x = 8 and in Bomarea x = 9. The three known subgenera of Bomarea are redefined, mainly on ovary and fruit characters, and a fourth subgenus is added. The members of subgen. Bomarea s.str. (c. 100 species) have an inferior ovary and a dehiscent capsule, in subgen. Sphaerine (c. 15) the plants are always not twining, they have an inferior ovary and indehiscent and strikingly coloured fruits. In subgen. Wichuraea (c. 15) the ovary is semi‐inferior, and the fruit is a dehiscent capsule. In Baccata Hofreiter subgen. nov. (3) the plants are twining, the ovary is inferior and develops into an indehiscent fruit with a thick fleshy pericarp. A key to determine the subgenera is given in English and Spanish. For each subgenus the typical growth forms and their variability, habitat preferences and general distribution are discussed. Field studies in Peru revealed a high variability within the populations of Bomarea. Based on these experiences the systematic value of different characters is discussed. In general, the vegetative characters were found to be most variable, while selected generative characters are appropriate to characterise systematic groups. The greatest amount of character variability was found in subgen. Wichuraea, the most constant characters are found in subgen. Sphaerine.

A New Fossil Flower and Associated Coprolites: Evidence for Angiosperm‐Insect Interactions in the Santonian (Late Cretaceous) of Georgia, U.S.A.

Plant‐insect interactions are readily identifiable in the fossil record when insect activities cause damage to plant tissues, for example, leaf mining, piercing, galls. However, the inference of insect pollination of extinct plants usually must be based on comparative morphology of plants and insects or based on phylogenetic relationships and pollination habits of extant taxa. The presence of insect coprolites can provide additional evidence supporting the inference of plant‐insect interactions based on the morphology and composition of the fossilized feces. In this article, we describe Noferinia fusicarpa gen. et sp. nov. based on fossil flowers and fruits recovered from the Buffalo Creek Member of the Gaillard Formation (late Santonian, Cretaceous) of central Georgia. The morphology of the flowers—differentiated perianth, basally connate calyx and corolla, inferior ovary, and possible nectiferous pores surrounding the base of the style—is consistent with generalized insect pollination. Associated with Noferinia flowers and fruits in the same sediment samples are five morphotypes of coprolites that are similar in shape and composition to the feces produced by modern beetles that feed on pollen and flowers. On the basis of the morphological features exhibited by Noferinia and by the coprolites containing its pollen, we suggest that Noferinia fusicarpa was insect pollinated.

Homologies of Inferior Ovaries and Septal Nectaries in Monocotyledons

The range of gynoecial structure in monocotyledons is examined in the context of current understanding of phylogenetic relationships, with particular reference to lilioid monocots, especially Asparagales. Major variations in gynoecial structure in lilioids include degree of syncarpy, occurrence and position of septal nectaries, and hypogyny versus epigyny. Structural evidence from septal nectaries, combined with recent molecular phylogenetic studies, indicates multiple origins of epigyny within monocots in general and Asparagales in particular, including possible separate de novo evolution of epigyny within the orchids and some other lower asparagoids. However, the infralocular septal nectaries that occur in genera of the sister clade to the higher asparagoids (e.g., Xanthorrhoea and Phormium) support a reversal from epigyny to hypogyny in this group, as indicated by optimization of this character on a recent phylogeny of Asparagales. The complex pattern of evolution of gynoecial structures in monocots ma...

Phylogenetic relationships in the Gesnerioideae (Gesneriaceae) based on nrDNA ITS and cpDNA trnL-F and trnE-T spacer region sequences.

The Gesnerioideae includes most of the New World members of the Gesneriaceae family and is currently considered to include five tribes: Beslerieae, Episcieae, Gesnerieae, Gloxinieae, and Napeantheae. This study presents maximum parsimony and maximum likelihood phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer regions (ITS), and the chloroplast DNA trnL intron, trnL‐trnF intergenic spacer region, and trnE‐trnT intergenic spacer region sequences. The ITS and cpDNA data sets strongly support the monophyly of a Beslerieae/Napeantheae clade; an Episcieae clade; a Gesnerieae clade; a Gloxinieae clade minus Sinningia, Sinningia relatives, and Gloxinia sarmentiana; and a Sinningia/Paliavana/Vanhouttea clade. This is the first study to provide strong statistical support for these tribes/clades. These analyses suggest that Sinningia and relatives should be considered as a separate tribe. Additionally, generic relationships are explored, including the apparent polyphyly of Gloxinia. Chromosome number changes are minimized on the proposed phylogeny, with the exception of the n = 11 taxa of the Gloxinieae. Scaly rhizomes appear to have been derived once in the Gloxinieae sensu stricto. The number of derivations of the inferior ovary is unclear: either there was one derivation with a reversal to a superior ovary in the Episcieae, or there were multiple independent derivations of the inferior ovary.

Diversity of Vascular System in the Wall of Inferior Ovary in the Family Asteraceae

Diversity of Vascular System in the Wall of Inferior Ovary in the Family Asteraceae

Floral structure and development and systematic aspects of some 'lower' Asparagales

Floral structure and development of representatives of Asteliaceae, Blandfordiaceae, Boryaceae, Doryanthaceae, and Hypoxidaceae, all members of the `lower' Asparagales, were studied comparatively. The results are discussed in the light of new molecular systematic studies, but also with regard to established morphological characters in related groups. Stamen shape varies considerably within and between taxa: the shape of anthers is from X-shaped, sagittate to non-sagittate, they are either latrorse or introrse, basifixed, centrifixed or dorsifixed. Gynoecia are syncarpous up to the stigmatic region in all taxa. Ovaries of Doryanthaceae and Hypoxidaceae are inferior, but they are superior in Asteliaceae, Blandfordiaceae and Boryaceae. All ovaries have at least a short synascidiate zone. With the exception of Astelia alpina (Asteliaceae), the ovaries are trilocular. Ovaries of Asteliaceae contain mucilage, which is secreted from trichomes on the funicle and on the placenta. Although flowers are polysymmetric at anthesis, they are monosymmetric in earliest stages with a developmental gradient from adaxial to abaxial. Perianth organs arise individually from either a concave (taxa with inferior ovary) or convex (taxa with superior ovary) apex. Hypoxidaceae have pollen flowers with free stamens. One species, Curculigo capitulata, has Solanum-type flowers with postgenitally united stamens. It is most probably pollinated by buzzing bees. All other taxa have nectariferous flowers with internal or external septal nectaries.

Ontogeny and morphology of the fertile flowers of Hydrangea and allied genera of tribe Hydrangeeae (Hydrangeaceae)

The monophyletic Hydrangeeae (Hydrangeaceae) consists of the cladeCardiandra +Deinanthe and its sister, the Hydrangea clade, which includes the paraphyleticHydrangea as well as Broussaisia, Decumaria, Dichroa, Pileostegia,Platycrater and Schizophragma. The plesiomorphic imbricate corolla aestivation and polystemony ofCardiandra and Deinanthe distinguish these two genera from most members of the Hydrangea clade.Deinanthe has postgenitally fused styles and cushion-like, dorsally positioned stigmas. The Hydrangea clade is notable because most species of Hydrangea share a floral morphology characterized by small size; tetramerous-pentamerous perianths; inconspicuous sepals; reflexed petals; diplostemony; stamens that are longer than the styles; completely inferior ovaries; separate styles; terminal, papillate stigmas; and dimerous-tetramerous gynoecia. This suite of states is termed the «Hydrangea floral syndrome» (HFS). Various members of the Hydrangea clade lack the HFS, including (1)Platycrater ; (2) Hydrangea anomala; (3) H. paniculata+H. heteromalla; (4) theSchizophragma clade (Schizophragma, Pileostegia and Decumaria); and (5) the macrophylla clade (H. macrophylla, H. scandens, H. hirta, Dichroa and Broussaisia). The meristic uniqueness of Decumaria reflects mutations observed in Arabidopsis (clavata) and Lycopersicon (fasciated) that cause organ number increases because of changes in meristem capital. The modification of early perianth development to form a prominent corolline torus at a point when sepals are diminutive is present in H. anomala andHydrangea section Cornidia and may be synapomorphic for them. Various transformations in the perianth, androecium, and gynoecium lie behind the floral diversity of Hydrangeeae. Some morphological transformations have been homoplastic, including shifts to polystemony, calyptrate corollas, and synstyly.

Ontogeny and morphology of the fertile flowers of Hydrangea and allied genera of tribe Hydrangeeae (Hydrangeaceae)

The monophyletic Hydrangeeae (Hydrangeaceae) consists of the cladeCardiandra +Deinanthe and its sister, the Hydrangea clade, which includes the paraphyleticHydrangea as well as Broussaisia, Decumaria, Dichroa, Pileostegia,Platycrater and Schizophragma. The plesiomorphic imbricate corolla aestivation and polystemony ofCardiandra and Deinanthe distinguish these two genera from most members of the Hydrangea clade.Deinanthe has postgenitally fused styles and cushion-like, dorsally positioned stigmas. The Hydrangea clade is notable because most species of Hydrangea share a floral morphology characterized by small size; tetramerous-pentamerous perianths; inconspicuous sepals; reflexed petals; diplostemony; stamens that are longer than the styles; completely inferior ovaries; separate styles; terminal, papillate stigmas; and dimerous-tetramerous gynoecia. This suite of states is termed the «Hydrangea floral syndrome» (HFS). Various members of the Hydrangea clade lack the HFS, including (1)Platycrater ; (2) Hydrangea anomala; (3) H. paniculata+H. heteromalla; (4) theSchizophragma clade (Schizophragma, Pileostegia and Decumaria); and (5) the macrophylla clade (H. macrophylla, H. scandens, H. hirta, Dichroa and Broussaisia). The meristic uniqueness of Decumaria reflects mutations observed in Arabidopsis (clavata) and Lycopersicon (fasciated) that cause organ number increases because of changes in meristem capital. The modification of early perianth development to form a prominent corolline torus at a point when sepals are diminutive is present in H. anomala andHydrangea section Cornidia and may be synapomorphic for them. Various transformations in the perianth, androecium, and gynoecium lie behind the floral diversity of Hydrangeeae. Some morphological transformations have been homoplastic, including shifts to polystemony, calyptrate corollas, and synstyly.

The North American ginseng inflorescence: development, floret abscission zone, and the effect of ethylene

Characterization of the North American ginseng (Panax quinquefolius L.) inflorescence, the floret abscission zone, and its stimulation by ethylene were undertaken to gain insights into the potential for floret abscission induction as a replacement for the industry practice of expensive manual removal of the inflorescence. In each of 3 years, peduncle length of 3-year-old cultivated ginseng inflorescences increased rapidly in June, reaching maximal values of 140–180 mm. During this period, seed head diameter also increased to about 35 mm, while seed head fresh mass increased in July and August to 6.5–8.0 g. Flowering in 1996 and 1997 began in the last 2 weeks of June and lasted through July, with open flowers never exceeding 35%. Anatomical studies and manual dissection of 1- and 3-year-old perennating buds revealed development of the floral primordia first at their periphery and progressing centripetally. Stamen initials were seen as a pentamerous whorl just under the petal primordia, and the characteristic inferior ovary initiated as a slight depression at the centre of the floral meristem. Sections through 3-year-old inflorescences harvested on May 23, 1996, showed that distal floral apices had already formed constriction zones between the flower and the pedicel, indicating the position of the abscission zone. Length of time to ethylene-induced abscission zone formation was less than 24 h in 3-year-old ginseng harvested on July 23, 1997. The abscission threshold for ginseng berry drop was in the range of 10-100 µL·L–1 ethylene.Key words: anatomy, flowering, Panax quinquefolius, perennating bud.

Floral Structure and Development ofApostasiaandNeuwiedia(Apostasioideae) and their Relationships to Other Orchidaceae

Floral development, structure, and pollination biology of species of Apostasia and Neuwiedia constituting the basalmost orchid subfamily Apostasioideae were studied. The perianth organs arise from a ring primordium. The two adaxial sepals appear first, followed by the petal primordia. This contrasts with monandrous orchids, in which the median petal primordium is the first organ of the inner perianth whorl to develop. Stamens are only formed on the abaxial side of the flower. However, in Neuwiedia veratrifolia and Apostasia nuda, vestiges of stamen primordia are present on the adaxial side of the flower. In Apostasia only, the lateral stamens are fully developed, whereas the median organ is a staminode; in A. nuda the staminode is suppressed. At anthesis the anthers are free in Neuwiedia, but they are postgenitally connected in Apostasia. In both genera, stamens and style are congenitally fused at the base. The inferior ovary is at first unilocular and then becomes trilocular by postgenital fusion of the ovary septa and the development of a short synascidiate zone. The three carpels of both genera are equal from the beginning, but in A. nuda only, the median carpel dominates during early development. The stigma is convex and papillate. Conspicuous raphide idioblast accumulations occur in staminode and style and in the tips of anthers and filaments. In contrast to all other orchids, both genera offer pollen as a reward. Neuwiedia has lip flowers, which are pollinated by Trigona bees; Apostasia has “Solanum‐type” flowers with recurved perianth and united anthers. Our study supports the view that Apostasia and Neuwiedia are closely related and that Apostasioideae are at the base of the orchid clade, sharing characters with orchids and lower Asparagales.

Structural homology and developmental transformations associated with ovary diversification in Lithophragma (Saxifragaceae)

Lithophragma, comprising only ten species, encompasses a remarkable diversity of ovary positions, reported to range from inferior to superior. The structural homology of the gynoecium and developmental transformations associated with ovary diversification are investigated for Lithophragma. Scanning electron and light microscopy indicate that all species of Lithophragma have epigynous flowers. Lithophragma campanulatum, L. glabrum, and L. heterophyllum have ovaries that externally appear nearly superior, but are actually shallowly inferior or "pseudosuperior." The inferior ovaries of Lithophragma species can be conceptually divided into superior and inferior regions that meet at the point of perianth and androecial insertion. Static and ontogenetic allometry reveal that across the species of Lithophragma the lengths of these two ovary regions are coordinated. Ovary regions in mature flowers display an approximately linear relationship that can be expressed through the allometric equation SL = -0.5314 IL + 2.0348 (where SL and IL are the lengths of the superior and inferior regions of the ovary, respectively; r = 0.7683, df = 35, P = 2.45 × 10). Mapping ontogenetic allometries onto a recent phylogeny for Lithophragma shows that ovary position evolution is bidirectional and has shifted toward greater superiority in some species and greater inferiority in others.

Floral Biology and Seed Production in Cultivated North American Ginseng (Panax quinquefolius)

Morphological characteristics of flowers, duration of flowering, degree of self-pollination, and extent of berry and seed production in North American ginseng (Panax quinquefolius L.) were studied under controlled environmental conditions as well as under field conditions. A comparison was also made between plants of 3 and 4 years of age at two field locations. The duration of flowering was ≈4 weeks and was similar in plants of both age groups grown in the two environments; however, 4-year-old plants produced an average of 40% more flowers (≈100 per plant in total) compared to 3-year-old plants. Flowers were comprised of five greenish-colored petals, five stamens, and an inferior ovary consisting of predominantly two fused carpels and stigmatic lobes. Anthers dehisced in staggered succession within individual flowers, and flowering began with the outermost edge of the umbel and proceeded inwards. At any given time during the 4-week flowering period, ≈10% of the flowers in an umbel had recently opened and were producing pollen. Stigma receptivity was associated with separation of the stigmatic lobes; this occurred at some time after pollen release. Growth of pollen tubes through the style in naturally pollinated flowers was most evident when the stigmatic lobes had separated. The proportion of flowers that developed into mature berries (pollination success rate) was in the range of 41% to 68% for both 3-year-old and 4-year-old plants. However, when the inflorescence was bagged during the flowering period, berry formation was increased by 13% to 21% in 4-year-old plants, depending on location. A majority of the berries (92% to 99%) contained one or two seeds in an almost equal frequency, with the remaining berries containing three seeds. In 4-year-old plants, the frequency of two-seeded berries was increased by ≈13% by bagging the inflorescence. These observations indicate that P. quinquefolius is highly self-fertile and that several physiological and environmental factors can affect seed production.

Plastid rbcL Sequence Data Show Dialypetalanthus to Be a Member of Rubiaceae

Dialypetalanthus fuscescens Kuhlm., endemic to Amazonia, has been treated as the sole member of Dialypetalanthaceae Rizzini & Occhioni. Various affinities have been suggested, but its phylogenetic position has remained unclear due to the unique combination of characters indicating an affinity with Rubiaceae (e.g. opposite leaves, interpetiolar stipules and an inferior ovary), in which family it was originally placed, or Myrtales (free petals and numerous stamens). Analysis of rbcL sequence data indicates that Dialypetalanthus is a member of Rubiaceae sensu stricto and falls in Ixoroideae sensu lato sensu Bremer with relatively strong bootstrap support (83%). Within the subfamily, Dialypetalanthus falls with a group of other neotropical taxa, but this position is not well supported. In the successively weighted trees Dialypetalanthus fell in a clade with the New World taxa Calycophyllum, Capirona, Condaminea, Hippotis, Pentagonia and Pogonopus. However, this clade received bootstrap support of <50%. On the basis of these data we recommend inclusion of Dialypetalanthus in Rubiaceae, but data for other loci and further morphological analysis will be required before its exact relationships can be determined.

Reversal in Ovary Position from Inferior to Superior in the Haemodoraceae: Evidence from Floral Ontogeny

Floral anatomy and development were studied in Wachendorfia thyrsiflora and Lachnanthes caroliniana of the monocot family Haemodoraceae in order to evaluate the hypothesis that a superior-ovary position arose from an ancestral inferior-ovaried condition. In Wachendorfia three conduplicate carpel primordia develop at the floral apex, followed by postgenital fusion forming a superior ovary. The lower receptacular tissue at the central floral axis elongates at about the same extent as the peripheral receptacular tissue. In the extended receptacular region, two lateral commissures develop by differential tissue growth, followed by differentiation of inner epithelial cells to form septal nectaries. The receptacular commissures and nectaries are continuous with carpellary commissures of the superior ovary. Junction of the median outer tepal vein and dorsal carpellary vein occurs well below the septal nectaries at the base of the receptacle. In Lachnanthes three small, conduplicate carpel primordia develop at the floral apex. Growth of the lower receptacular tissue at the central floral axis is relatively retarded, such that the peripheral tissues elongate differentially, surrounding the now laterally positioned carpels. Subsequent postgenital fusion results in an inferiorovary position, relative to perianth insertion. Incomplete postgenital fusion of intercarpellary spaces results in the formation of septal commissures. These commissures later mature into septal nectaries, which extend to the apex of the inferior ovary. Junction of the median outer tepal vein and dorsal carpellary vein occurs just beneath the ovary locules. It is proposed that the floral receptacular region of Wachendorfia and of other superior-ovaried Haemodoraceae is homologous with an ancestral inferior ovary with regard to position, development, and vasculature. A superior ovary in the Haemodoraceae arose by the co-option of an ancestral inferior ovary into an elongated receptacle, along with extension of the intercarpellary commissures to the periphery of the receptacular tissue, and modification of those peripheral commissures to nectaries The adaptive significance of this evolutionary event is unclear but apparently related to a shift in pollination mechanism

Theligonum cynocrambe: Developmental morphology of a peculiar rubiaceous herb

The annual Mediterranean herbTheligonum cynocrambe shows a peculiar combination of morphological characters, e.g., switch from decussate to spiral phyllotaxis with 90–100° divergence, combined with a change from interpetiolar to lateral stipules, anemophily, lack of calyx, flowers often dimerous to trimerous, corolla fused in both male and female flowers, male flowers extra-axillary, with 2–19 stamens per flower, female flowers axillary, with inferior uniovulate ovary, basilateral style and perianth, nut-like fruits with elaiosome. In male flowers the androecium emerges as an (uneven) elliptical rim with a central depression. This common girdling primordium is divided up into several stamen primordia. In male flowers with low stamen number the stamen primordia may occupy the corners alternating with the corolla lobes. There are no epipetalous androecial primordia that secondarily divide into stamens. Male flowers occasionally show a hemispherical base that may be interpreted as remnant of the inferior ovary. In female flowers a ring primordium grows into a tube on which the petal lobes arise. The perianth and style become displaced adaxially by uneven growth of the inferior ovary. The ovary is basically bilocular. The lower region of the ovary is provided with a septum that is overtopped and hidden by the single curved ovule.Theligonum is referred to theRubiaceae-Rubioideae, with theAnthospermeae andPaederieae as most closely related tribes.

A cladistic analysis of Asarum (Aristolochiaceae) and implications for the evolution of herkogamy

A cladistic analysis of Asarum was conducted to examine relationships among species within the genus and to test the monophyly of several groups of taxa that have often been treated as segregate genera. Thirty-two species were drawn from throughout the range of the genus, representing a broad sample of sections and all segregate genera. The data matrix included 37 characters derived from various aspects of vegetative and floral morphology. A strict consensus of all most parsimonious trees suggests that Asarum s.l. is monophyletic and consists of two main clades: an Asarum clade, which is characterized by connate styles and inferior ovaries, and an Asiasarum-Hexastylis-Heterotropa clade, which is characterized by ridges on the inner perianth surface, dorsal stigmas, and bifid style extensions. The latter is a large and morphologically diverse clade that includes the North American segregate Hexastylis and two Asiatic segregates. Examination of pollination mechanisms in the context of this phylogeny supports the conclusion that herkogamy, and thus obligate insect pollination, is derived from a plesiomorphic condition of autonomous self-pollination. Associated with herkogamy are characters such as glandular trichomes and other ornamentation of the surface of the calyx that probably represent increased specialization to attract insect pollinators. This study also indicates that chromosomal evolution has occurred via aneuploid decrease from an ancestral chromosome number of 2n = 26 to 2n = 24 in Heterotropa. The recognition of two subgenera, subgenus Asarum and subgenus Heterotropa, corresponding to the two clades in the cladistic analysis, is recommended.

Embryology and circumscription of Campanulaceae and Campanulales: A review of literature

Embryological studies of Campanulaceae and related families were reviewed to add to discussion of appropriate circumscription of Campanulaceae and Campanulales. Embryological features are very uniform within Campanulaceaesens. lat. (Campanuloideae and Lobelioideae), and provide no evidence for the separation of Lobelioideae as a distinct family. Campanulaceaesens. lat. share with several other families traditionally included in Campanulales (or Asterales) a few derived embryological features (i.e., unitegmic and tenuinucellate ovules, an endothelium,ab initio Cellular type endosperm, and an endosperm haustorium). However, an extensive comparison with families in an expanded Asteridae shows that those derived embryological features are symplesiomorphies, rather than synapomorphies indicative of close relationships among them. Combined with other morphological (inferior ovary), chemical (presence of inulin), and molecular (rbcL gene nucleotide sequence) characters, embryological features rather support a broad circumscription of Campanulales (or Asterales) including Pentaphragmataceae, Stylidiaceae, Campanulaceaesens. lat., Donatiaceae, Menyanthaceae, Calyceraceae, Goodeniaceae, and Asteraceae. Within Campanulalessens. lat. (or Asteralessens. lat.), Menyanthaceae, Calyceraceae, Goodeniaceae, and Asteraceae are obviously closely related to one another. To understand more exact relatonships within the order, embryological studies are needed onBrunonia, Cyphia, Cyphocarpus, Nemacladus, Corokia, Abrophyllum, Argophyllaceae, and Alseousmiaceae.

Fruit Growth and Development of Muskmelon (Cucumis melo var. reticulatus Naud.)

As part of a program to develop a model for growth and development of muskmelon produced under various mulch and row cover combinations, all perfect flowers of five plants were tagged and measured on a daily basis. The polar and equatorial lengths of the inferior ovary were recorded from anthesis to fruit maturity. Mature fruits were harvested at full slip. The location of each flower on the plant was coded. Flowers and subsequent fruits were classified according to the following phenological stages: immature, close to mature, close to full bloom, full bloom, wilted, past full bloom, close to fruit, fruit. The netting was visually evaluated and rated on a scale of 0 to 5, the highest value representing maximum netting. At fruit maturity, the weight, polar and equatorial length of each fruit were measured and mature and immature seeds counted. The number of fruits that reached maturity was directly proportional to the total number of perfect flowers produced on a plant. Fruit weight during growth could be predicted from the polar and equatorial lengths.

A Chloroplast DNA Study of the Agavaceae

A chloroplast DNA restriction site analysis of 40 taxa in the Agavaceae s.l. was undertaken to test the accuracy of several current systems of classification. In Cronquist's system, the Agavaceae contain 18 genera of fibrous-leaved, more or less woody plants such as Yucca, Hes- peraloe, Agave, Manfreda, Polianthes, Dracaena, Sansevieria, Nolina, Beaucarnea, Dasylirion, and Cordyline. In Dahlgren's system, the Agavaceae are restricted to Yucca, Hesperaloe Agave, Manfreda, Polianthes, Beschorneria, and Furcraea, while the other genera are placed in different families. These contrasting phylogenetic schemes were investigated by a chloroplast DNA restriction site analysis of these genera plus Xanthorrhoea, Hosta, Hypoxis, Hemerocallis, Asparagus, Liriope, Aspidistra, Maianthemum, and Convallaria. Phylogenetic analysis of 110 restriction site mutations, 90 of which were phylo- genetically informative, strongly supports the conclusion that there are two major lineages in this group of taxa. One well supported clade contains, sensu Dahlgren, the Nolinaceae, Dracaenaceae, and Convallariaceae. It appears that Nolina and Dasylirion are more closely related to genera such as Liriope, Maianthemum, and Dracaena than to Yucca and Agave. The other major lineage contains Yucca, Hesperaloe, Agave, Manfreda, Polianthes, Beschorneria, and Furcraea, with Hosta and perhaps Xanthorrhoea at the base. Asparagus appears to be intermediate between the two lineages. The cpDNA suggests that Cordyline, Hypoxis, and Hemerocallis are not closely related to the Agavaceae. A major problem in monocot taxonomy con- cerns the classification and phylogeny of the genera in the Liliaceae s.l. and smaller families that have been split off from it, such as the Agavaceae. Two distinct systems of classifica- tion have been proposed and both are in use at the present time (Cronquist 1981; Dahlgren et al. 1985). The apparent frequency of convergent and parallel evolution of characters in these taxa makes it difficult to recover the phylogeny us- ing morphological characters alone. In this pa- per these problems are examined using evi- dence from chloroplast DNA restriction site analysis. In the traditional taxonomic systems of Ben- tham and Hooker (1883) and Engler and Prantl (1888), most liliaceous plants with a superior ovary, including Yucca L. and Dasylirion Zucc., were placed in a broadly conceived Liliaceae with many tribes, while those with an inferior ovary, such as Agave L., were placed in the Amaryllidaceae. Hutchinson (1934) is generally

Utility of Ontogenetic and Conventional Characters in Determining Phylogenetic Relationships of Saururaceae and Piperaceae (Piperales)

Morphological and developmental evidence is utilized in a phylogenetic analysis of Piperales. Best resolution of trees was obtained by combining ontogenetic data with conventional morphological data. Floral ontogeny provides a means to determine homology among character states as well as to provide additional characters not observable in mature flowers. Both Lundberg and outgroup rooting were performed using a hypothetical ancestor defined by general ontogenetic states in the former and by five taxa presumably related to the ingroup in the latter. Polarization of character states via ontogenetic generality principles is congruent with outgroup polarization. Saururaceae and Piperaceae are each monophyletic. Saururaceae are supported by three synapomorphies, with Saururus as the basal taxon. The other three saururaceous genera (Anemopsis, Houttuynia, Gymnotheca) share the derived character slates of syncarpy, stamen-carpel adnation, and an inferior or half-inferior ovary. Piperaceae are supported by seven synapomorphies with Zippelia as the basal taxon. Six other synapomorphies unite the remaining Piperaceae suggesting that Macropiper and Pothomorphe are specialized offshoots of the morphologically variable Piper. Numerous autapomorphies support Peperomia as a distinct and specialized offshoot within Piperaceae. Within the sister clades Saururaceae and Piperaceae, there are parallel reduction trends in floral organ number and in the sequence of floral organ initiation.