Comparative seed morphology of <Emphasis Type="Italic">Leandra</Emphasis> (Miconieae,Melastomataceae)

The seed morphology of 79 species of neotropical Miconieae (Melastomataceae) is presented. These species have been chosen, in majority, from the polyphyletic genus Leandra. A few other species from the polyphyletic genera Miconia, Ossaea, and Clidemia were also sampled, because of potential similarities. Sixteen morphological seed types are defined after analysis through light microscopy and scanning electron microscopy. The seed morphology appears to possess a great deal of variability on the level of the overall shape as well as the structure and the surface of the testa. The different types defined here do not match with genera or sections, but rather are composed of species coming from different genera. In comparison with a preliminary molecular phylogeny study done on Leandra, some types of seeds are related to well supported clades. In some cases seed morphology corresponds with natural groups of species, thus being of high phylogenetic importance.     

Phylogeny and classification of the Melastomataceae and Memecylaceae

A systematic analysis of the Melastomataceae, a pantropical family of about 4200–4500 species in c. 166 genera, and their traditional allies, the Memecylaceae, with c. 430 species in six genera, suggests a phylogeny in which there are two major lineages in the Melastomataceae and a clearly distinct Memecylaceae. Melastomataceae have close affinities with Crypteroniaceae and Lythraceae, while Memecylaceae seem closer to Myrtaceae, all of which were considered as possible outgroups, but sister group relationships in this plexus could not be resolved. Based on an analysis of all morphological and anatomical characters useful for higher level grouping in the Melastomataceae and Memecylaceae a cladistic analysis of the evolutionary relationships of the tribes of the Melastomataceae was performed, employing part of the ingroup as outgroup. Using 7 of the 21 characters scored for all genera, the maximum parsimony program PAUP in an exhaustive search found four 8-step trees with a consistency index of 0.86. Because of the limited number of characters used and the uncertain monophyly of some of the tribes, however, all presented phylogenetic hypotheses are weak. A synapomorphy of the Memecylaceae is the presence of a dorsal terpenoid-producing connective gland, a synapomorphy of the Melastomataceae is the perfectly acrodro-mous leaf venation. Within the Melastomataceae, a basal monophyletic group consists of the Kibessioideae (Prernandra) characterized by fiber tracheids, radially and axially included phloem, and median-parietal placentation (placentas along the mid-veins of the locule walls). A second clade, the Melastomatoideae, with libriform fibers and lacking included phloem, and with axile-basal or axillary placentation, comprises the remainder of Melastomataceae and consists of eight reasonably well differentiated tribes, one of them paleotropical (Astronieae), three pantropical (Sonerileae, Melasto-meae, and Miconieae), and four neotropical (Merianieae, Microlicieae, Rhexieae, and Blakeeae). The Astronieae have several plesiomorphic characters, such as anthers opening by two slits and axile-basal placentation; all other clades have primarily poricidal anthers' and consistently axillary placentas. A new subfamilial and tribal classification based on the analysis includes an annotated list of all currently recognized genera with numbers of species, distribution and important synonyms. Significant features of the classification include: the placement of Pternandra in a subfamily of its own and the dissolution of the Astronioideae; the merger of three neotropical and paleotropical tribal pairs; and the placement of Rhexia in a tribe of its own. Biogeo-graphy, fossil history, and hypothesized phylogeny of the Melastomataceae imply an east Gondwanian origin of the family.     

Molecular phylogenetics of Melastomataceae and Memecylaceae: implications for character evolution

Melastomataceae are among the most abundant and diversified groups of plants throughout the tropics, but their intrafamily relationships and morphological evolution are poorly understood. Here we report the results of parsimony and maximum likelihood (ML) analyses of cpDNA sequences from the rbcL and ndhF genes and the rpl16 intron, generated for eight outgroups (Crypteroniaceae, Alzateaceae, Rhynchocalycaceae, Oliniaceae, Penaeaceae, Myrtaceae, and Onagraceae) and 54 species of melastomes. The sample represents 42 of the family's currently recognized ～150 genera, the 13 traditional tribes, and the three subfamilies, Astronioideae, Melastomatoideae, and Memecyloideae (= Memecylaceae DC.). Parsimony and ML yield congruent topologies that place Memecylaceae as sister to Melastomataceae. Pternandra, a Southeast Asian genus of 15 species of which five were sampled, is the first- branching Melastomataceae. This placement has low bootstrap support (72%), but agrees with morphological treatments that placed Pternandra in Melastomatacaeae because of its acrodromal leaf venation, usually ranked as a tribe or subfamily. The interxylary phloem islands found in Memecylaceae and Pternandra, but not most other Melastomataceae, likely evolved in parallel because Pternandra resembles Melastomataceae in its other wood characters. A newly discovered plesiomorphic character in Pternandra, also present in Memecylaceae, is a fibrous anther endothecium. Higher Melastomataceae lack an endothecium as do the closest relatives of Melastomataceae and Memecylaceae. The next deepest split is between Astronieae, with anthers opening by slits, and all remaining Melastomataceae, which have anthers opening by pores. Within the latter, several generic groups, corresponding to traditional tribes, receive solid statistical support, but relationships among them, with one exception, are different from anything predicted on the basis of morphological data. Thus, Miconieae and Merianieae are sister groups, and both are sister to a trichotomy of Bertolonieae, Microlicieae + Melastomeae, and Dissochaeteae + Blakeeae. Sonerileae/Oxysporeae are nested within Dissochaeteae, Rhexieae within Melastomeae, and African and Asian Melastomeae within neotropical Melastomeae. These findings have profound implications for our understanding of melastome morphological evolution (and biogeography), implying, for example, that berries evolved from capsules minimally four times, stamen connectives went from dorsally enlarged to basal/ventrally enlarged, and loss of an endothecium preceded poricidal dehiscence.     

Taxonomic significance of pollen types in the Guyana Highland-centred composite genera of Mutisioideae (Asteraceae)

The Guyana Highland-centred genera, or Stenopadus group, are a complex of species that belong to the tribes Mutisieae and Stifftieae of Asteraceae. The pollen morphologies of 29 species, from 12 of 13 genera of this complex, are described and illustrated using light and scanning electron microscopy. The exine sculpture and structure are highly significant. Four exine types, previously characterized, were distinguished: Gongylolepis , Wunderlichia , Mutisia , and Stenopadus . The characterization of the Stenopadus exine type is enlarged here. These exine types led to the recognition of four well-defined pollen types, whereas the spine length and exine thickness characterized six subtypes. Pollen types circumscribe genera or groups of genera, and some subtypes distinguish species. The pollen morphology within the complex is discussed in relation to the rest of Mutisioideae and other palynologically allied tribes of Cichorioideae. There is little correlation between pollen types and tribes; only the Stenopadus exine type is exclusive to the Stifftieae tribe. The remaining types are shared by the two tribes of the complex. Pollen morphology supports the hypothesis that this group of genera is close to the Gochnatia complex and the Cardueae tribe.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 327–340.     

Phylogenetic reassessment of the five forewing radial-veined tribes of Riodininae (Lepidoptera: Riodinidae)

The relationships among the genera and tribal groupings of Riodininae with five forewing radial veins, and between these and tribes with four forewing radial veins, were examined using a phylogenetic analysis. Using the type species from all sixteen genera in the tribal groupings Eurybiini, Mesosemiini and incertae sedis (a presumed paraphyletic group of loosely related genera), and representatives from the four forewing radial‐veined riodinine tribes, thirty‐five new and traditional characters were coded from adult ecology, wing venation and pattern, the adult head and body, male and female genitalia, and early stage ecology and morphology. The majority of characters are illustrated. Phylogenetic analysis of these data produced five equally most parsimonious cladograms using equal weights and after successive weighting. The strict consensus of these confirms the monophyly of Eurybiini and Mesosemiini as currently conceived, but also indicates several higher‐level relationships not previously hypothesized. Mesosemiini is here more broadly defined to also include the entire incertae sedis section, and the tribe is divided into Mesosemiina, for the previously delimited Mesosemiini plus Eunogyra and Teratophthalma, and Napaeina, subtr.n. for the incertae sedis section minus these two genera. The following hypothesis of relationships is tentatively proposed for the basal clades of Riodininae: Mesosemiini + (Eurybiini + remainder of Riodininae). These new hypotheses, and the characters supporting them, are discussed and compared with those previously proposed.     

金缕梅科的种子形态学及其系统学评价

本文利用光学显微镜及扫描电镜在属级水平上观察了金缕梅科全部6亚科中的21属41种1变种植物的种子特征,结果表明：该科的种子形状、颜色、大小及种脐特征在各亚科中有差异(除了双花木亚科与金缕梅亚科的大多数属是一致的)可作为区分亚科的特征之一。根据种皮的特征,可划分为5类：(1)种皮平滑或仅在边缘部分具条纹状纹饰(双花木亚科及金缕梅亚科中大部分属);(2)种皮具条纹状纹饰,条纹有波浪加厚或升高(马蹄荷亚科);(3)种皮具瘤状纹饰或具条纹和瘤状相间排列的纹饰(红花荷亚科);(4)种皮具条一网状纹饰(壳菜果亚科);(5)种皮具网状纹饰(枫香亚科)。种皮纹饰对亚科的划分具有一定意义。此外,还详细观察了该科的种皮结构,确认金缕梅科的种皮由外种皮及内种皮构成,而外种皮又进一步划分为外层、中层和内层,种皮各层的细胞层数对该科的分类价值不大。研究结果还表明：枫香亚科的种子特征明显不同于该科的其它成员。关于枫香亚科的系统位置还需深入研究。     

A phylogenetic evaluation of Leandra (Miconieae, Melastomataceae): a polyphyletic genus where the seeds tell the story, not the petals

Melastomataceae is a tropical family of 4500–5000 species divided into nine tribes. The largest tribe, Miconieae, is composed of approximately 2200 species in 30 genera and is found exclusively in the Neotropics. Previous phylogenetic analyses of the Miconieae have suggested that many of the genera are derived from a paraphyletic Miconia. However, these analyses only included six species of the large genus Leandra, so its phylogenetic affinities remained unclear. As currently defined Leandra is characterized by acute petals and terminal inflorescences, but some species of Miconia, Clidemia and Ossaea also have these characters. In this study, we present an analysis of nrITS sequence data for a sample of 63 species of Leandra. The genus is clearly resolved as polyphyletic, but some distinct and well‐supported clades exist. Some of these partially correspond to sections recognized in the nineteenth century by Cogniaux, or to geographic distribution. The distribution of seed structure characters is better correlated with the phylogeny than traditional characters, such as petal morphology. Seed appendages in Leandra have evolved independently at least four times. © The Willi Hennig Society 2007.     

SPORE MORPHOLOGY IN THE CYATHEACEAE. II. THE GENERA LOPHOSORIA,METAXYA, SPHAEROPTERIS,ALSOPHILA, AND NEPHELEA

Scanning electron microscopy and transmitted light microscopy are used in a palynological study of Lophosoria, Metaxya, Sphaeropteris, Alsophila, and Nephelea of the tree fern family Cyatheaceae. The monotypic American genera Lophosoria and Metaxya each have a unique spore morphology which reinforces the taxonomic distinctness of these genera as indicated by their other characters. All investigated paleotropical species of Sphaeropteris develop a single type of perine characterized by coarse, pointed projections. In the neotropics, the Sphaeropteris horrida group shares this perine type, whereas all other neotropical Sphaeropteris species appear to have a different kind of perine with fine hair-like processes. The exine in paleotropical Sphaeropteris appears uniformly unsculptured, whereas in the neotropics several exine morphologies are found. In Alsophila all investigated neotropical species and the vast majority of the paleotropical species are characterized by a basically ridged perine morphology and an unsculptured exine. In several paleotropical Alsophila species, however, a perine with hair-like processes similar to those in neotropical Sphaeropteris is found, and the exine in several species is variously pitted. In at least one paleotropical Alsophila species, the porate exine morphology is indistinguishable from that in the neotropical genus Cnemidaria. The spores of the American genus Nephelea are similar to those of the majority of Alsophila species in ridged perine morphology and unsculptured exine. Several new instances of atypical spore numbers per sporangium are reported in Sphaeropteris and Alsophila. These and the palynological data are discussed in a taxonomic framework. The spore morphology in these genera is consistent with Tryon's recent generic revision of the family.     

SILICON IN THE ROOTS OF HIGHER PLANTS

Silicon (Si) distribution in the roots of Sorghastrum nutans (L.) Nash and Sorghum bicolor (L.) Moench. was investigated by means of the electron-probe microanalyzer and scanning electron microscope. In both species, Si was confined to the inner tangential wall of the tertiary-phase endodermal cells in the form of nodular silica aggregates of similar morphology and X-ray intensity. The results are compared to those for six closely related genera, as well as to studies of Si in the roots of species of other tribes of the family Poaceae. The various types of root deposits occurring in the family are described, and their relationships discussed. It is concluded that the type of Si distribution exhibited is determined largely by the phylogenetic status of the genus, rather than by the basic pattern of root anatomy.     

Observations on the fruits and seeds of neotropical Lecythidaceae

Fruit characteristics, embryo types, and funicle-aril features are described for the genera of neotropical Lecythidaceae. Their bearing on the taxonomy of the family is discussed and a generic key based on fruit and seed features is provided. The anomalous seed structure ofAsteranthos brasiliensis is pointed out. Known fruit and seed adaptations for dispersal are described.     

Ovules and seeds in Acalyphoideae (Euphorbiaceae): structure and systematic implications

Acalyphoideae, the largest subfamily of Euphorbiaceae, are investigated with respect to ovule and seed structure on the basis of 172 species of 80 genera in all 20 tribes of Acalyphoideae sensu Webster. All species of Acalyphoideae examined have bitegmic ovules with a non-vascularized inner integument. However, noticeable differences exist among and sometimes within the genera in the thickness of the inner and outer integument, the presence or absence of vascular bundles in the outer integument, whether ovules are pachychalazal or not, the presence or absence of an aril, seed coat structure (in terms of the best-developed mechanical cell-layer), and the shape of cells constituting the exotegmen. For the latter two characters, two different types of seed coat (i.e., "exotegmic" and "exotestal") and three different types of exotegmic cell (i.e., palisadal, tracheoidal and ribbon-like) were distinguished. Comparisons showed that three tribes Clutieae, Chaetocarpeae and Pereae are distinct from the other Acalyphoideae as well as from the other Euphorbiaceae in having an exotestal seed coat with a tracheoidal exotegmen. The tribe Dicoelieae is also distinct from the other Acalyphoideae in having an exotegmic seed that is composed of ribbon-like cells of exotegmen (i.e., cells both longitudinally and radially elongated, sclerotic and pitted). The tribe Galearieae, which should be treated as a distinct family Pandaceae, is also distinct from the other Acalyphoideae in having an exotegmic seed with a tracheoidal exotegmen (i.e., cells longitudinally elongated, sclerotic and pitted). The remaining genera of Acalyphoideae always have an exotegmic seed with a palisadal exotegmen (i.e., cells radially elongated, sclerotic and pitted). The shared palisadal exotegmen supports the close affinity of Acalyphoideae (excluding five tribes) with Crotonoideae and Euphorbioideae. Within the remaining genera of Acalyphoideae, a significant diversity is found in ovule and seed morphology with respect to the thickness of the inner and outer integument, the size of chalaza, vascularization of an outer integument and an aril.     

SEM and Light Microscope Observations on Fruit and Seeds in Scrophulariaceae from Southwest Spain and their Systematic Significance

Many studies of the morphology and anatomy of fruits and seedsof Scrophulariaceae from Southwest Spain have been made. Thesystematic utility of characteristics of these plant structuresis discussed in order to determine relationships among the differentgenera included in this widely distributed family. The mostuseful fruit features for this study were the indumentum, capsuledehiscence and structure of the endocarp, seed-coat ornamentation,and inner structure of the seeds. In addition, phenetic analysisof 58 characters revealed that several groups of genera in Scrophulariaceaeare closely related on the basis of their fruit and seed features.The phenetic relationships of genera or groups of genera arediscussed. Keys to genera considered in this work, using exclusivelyfruit or seed characters, are provided. Lastly, the usual dispersalsystems observed in this family are discussed. Copyright 2000Annals of Botany Company Fruit, seed, morphology, anatomy, Scrophulariaceae, phenogram, SEM, pericarp, dehiscence, indumentum, seed-coat     

Gallery forest types and their environmental correlates in a Colombian savanna landscape

Savanna regions may contain significant areas of forest, usually in riparian environments. We described forest composition and quantified environmental variables for 80 plots in the watershed of the Yucao River (2550 km²), a tributary to the Meta River (Orinoco basin) in the eastern plains of Colombia. The total sampled area of 3.2 ha contained 147 tree species (110 genera and 45 families) with diameter at breast height >5 cm. The families represented by most species were Leguminosae (15 species), Arecaceae (11 species), Rubiaceae (9), Chrysobalanaceae (7), Euphorbiaceae (7), Melastomataceae (7) and Myrtaceae (7). Although most of the tree species have wide distribution ranges in humid neotropical forests, and few are endemic to the region, comparison with other neotropical forests suggests that the combination of taxa is characteristic for neotropical gallery forests. Cluster analysis allowed the definition of five forest types. They show important differences in a number of environmental variables, especially those related to inundation regimes and soil properties. Canonical correspondence analysis indicates good correlation of the first ordination axis with the size of the stream with which the forest is associated, the height to which the water rises during floods and variables related to soil fertility. The second ordination axis differentiates between soils with high or low water content in the dry season, high or low organic matter content and low or high bulk density. The results demonstrate the role of spatial variability and interactions of floodplain morphology, hydrological regime, and soil properties in structuring this important riparian community.     

Correlations among fruit traits and evolution of different fruits within Melastomataceae

The anatomy and morphology of nearly mature fruits in 85 mainly palaeotropical species of Melastomataceae were examined using microtome- and hand-sectioning, and differential staining. Much structural heterogeneity was observed in both capsules and berries. Mul-tivariate analyses of 31 of the 52 characters recorded for each species, revealed that indehiscence is associated with fusion of ovary and hypanthium tissues, placenta persistence, lack of a persistent endocarp, and a dearth of srlereids in these tissues, while dehiscenre is correlated with the opposite states and a persistent exocarp. Other fruit characters such as lignification or fleshiness of tissues do not show a consistent association with dehiscence. Break down of broad fruit types, such as 'berry' and 'capsule', into their individual morphological and anatomical traits shows how unusual fruit types, such as woody berries, fleshy capsules, and capsules containing fleshy placentas (display fruits), which are common in palaeotropical Melastomeae and Dissochaeteae, contribute to a loosening of expected correlations. Thus, discriminant analysis clearly differentiated display fruits from the other fruit types because of their combination of fleshy placentas with a persistent endocarp and absence of ovary/hypanthium fusion. The evolution of fruit types within Melastomataceae, and especially Dissochaeteae, and their reliability as phylogenetic indicators is discussed in the light of molecular phylogenies for these groups that show that berries and capsules evolved several times independently, explaining the observed heterogeneity of outwardly similar fruits. Fruit diversity within Melastoma , a monophyletic genus of 22 species, provides an example of the plasticity afforded by the particular construction of Melastomataceae fruits, which has contributed to ecological diversification in melastome seed dispersal.     

A survey on the intraclear inclusions in the Schrophulariaceae and their systematic significance

A survey of nuclear inclusions in chlorenchyma cells is given for 290 taxa of the Scrophulariaceae, covering 72 genera; 172 are new data and the remainder are from previous reports by the author. In addition to the 5 types of nuclear inclusions already determined by their different ultrastructural morphology — amorphous (A), lamellar (L), fibrillar (F), tubular (T), and crystalline (C) — and to subtypes C2, three new subtypes — A2, L2, T2 - specific to certain genera or small groups of genera are reported. These new subtypes are described in detail and their distribution in the family discussed. Although the proteinic nature was unquestionably demonstrated, the origin and function of plant nuclear inclusions is far from being understood. In the Scrophulariaceae they have been recognized in 242 out of 290 taxa studied (83.4%), in a total of 60 out of 72 genera (83.3%). On the basis of the occurrence and qualitative distribution of the nuclear inclusions, the family can be subdivided into four main group: 1) with lamellar inclusions, 2) with amorphous inclusions, 3) with inclusions other than those in the two former groups, and 4) with no nuclear inclusions. The relationship between the distribution on the nuclear inclusions throughout the family and the current systematic arrangement into subfamilies are analyzed and the transfer of some genera to different tribes or to a tribe of their own is proposed, e.g., in the case of Mimulus, Leucocarpus, Halleria, Russelia, Angelonia, Rehmannia , and Campylanthus . Finally, a possible evolutionary trend of the different types of nuclear inclusions based on their structural complexity and on the occurrence in allied families is offered.     

国产藜科14种植物种皮微形态特征比较研究

应用扫描电子显微镜和光学显微镜观察了中国产藜科(Chenopodiaceae)5族10属14种植物的种子形态和种皮微形态结构。观察结果表明:供试的14种藜科植物的种子多为卵形和圆形,少数为双凸镜形;种皮表面都具有网状纹饰,包括浅网纹、负网纹和穴状网纹。种皮可分为膜质和壳质2类,其中,膜质型种皮表面不光滑,除网状纹饰外,还有瘤状或褶皱状等纹饰,网眼无规则,纹饰排列无序,猪毛菜族(Salsoleae C.A.Mey.)的松叶猪毛菜(Salsola laricifolia Turcz.ex Litv.)及樟味藜族(Camphorosmeae Moq.)的地肤〔Kochia scoparia(L.)Schrad.〕、全翅地肤(K.krylovii Litv.)、黑翅地肤(K.melanoptera Bunge)、雾冰藜〔Bassia dasyphylla(Fisch.et Mey.)O.Kuntze〕、钩刺雾冰藜〔B.hyssopifolia(Pall.)O.Kuntze〕、樟味藜(Camphorosma monspeliaca L.)、兜藜(Panderia turkestanica Iljin.)和棉藜(Kirilowia eriantha Bunge)均属此类;壳质型种皮表面近光滑,网眼规则,排列整齐有序,少数为不规则浅穴,网脊平而不明显或凹陷,滨藜族(Atripliceae C.A.Mey.)的滨藜〔Atriplex patens(Litv.)Iljin.〕、碱蓬族(Suaedeae Reich.)的角果碱蓬〔Suaeda corniculata(C.A.Mey.)Bunge〕、纵翅碱蓬〔S.pterantha(Kar.et Kir.)Bunge〕和异子蓬(Borszczowia aralocaspica Bunge)以及藜族(Chenopodieae C.A.Mey.)的刺藜(Chenopodium aristatum L.)均属此类。各族之间种皮微形态结构也有一定的区别。根据种皮微形态,地肤属(Kochia Roth)与雾冰藜属(Bassia All.)的关系较近,属的界限和部分种类的亲缘关系需要进一步界定。藜科植物种皮表面大部分凹凸不平,这种结构可能与荒漠干旱生境下吸收和保留水分有关。     

Brassicaceae phylogeny and trichome evolution

To estimate the evolutionary history of the mustard family (Brassicaceae or Cruciferae), we sampled 113 species, representing 101 of the roughly 350 genera and 17 of the 19 tribes of the family, for the chloroplast gene ndhF. The included accessions increase the number of genera sampled over previous phylogenetic studies by four-fold. Using parsimony, likelihood, and Bayesian methods, we reconstructed the phylogeny of the gene and used the Shimodaira-Hasegawa test (S-H test) to compare the phylogenetic results with the most recent tribal classification for the family. The resultant phylogeny allowed a critical assessment of variations in fruit morphology and seed anatomy, upon which the current classification is based. We also used the S-H test to examine the utility of trichome branching patterns for describing monophyletic groups in the ndhF phylogeny. Our phylogenetic results indicate that 97 of 114 ingroup accessions fall into one of 21 strongly supported clades. Some of these clades can themselves be grouped into strongly to moderately supported monophyletic groups. One of these lineages is a novel grouping overlooked in previous phylogenetic studies. Results comparing 30 different scenarios of evolution by the S-H test indicate that five of 12 tribes represented by two or more genera in the study are clearly polyphyletic, although a few tribes are not sampled well enough to establish para- or polyphyly. In addition, branched trichomes likely evolved independently several times in the Brassicaceae, although malpighiaceous and stellate trichomes may each have a single origin.     

Comparative anatomy and morphology of nectar-producing Melastomataceae

Background and Aims

Most neotropical Melastomataceae have bee-pollinated flowers with poricidal anthers. However, nectar rewards are known to be produced in about 80 species in eight genera from four different tribes. These nectar-producing species are pollinated by both vertebrates and invertebrates.

Methods

The floral morphology and anatomy of 14 species was studied in six genera of nectar-producing Melastomataceae (Blakea, Brachyotum, Charianthus, Huilaea, Meriania and Miconia). Anatomical methods included scanning electron microscopy, and serial sections of paraffin-embedded flowers.

Key Results

All vertebrate-pollinated melastome flowers have petals that do not open completely at anthesis, thus forming a pseudo-tubular corolla, while closely related species that are bee pollinated have rotate or reflexed corollas. In most species, nectar secretion is related to stomatal or epidermal nectaries and not filament slits as previously reported. Moreover, the nectar is probably supplied by large vascular bundles near the release area. Blakea and Huilaea have nectary stomata located upon the dorsal anther connective appendages. Brachyotum also has nectary stomata on the anther connectives, but these are distributed lengthwise along most of the connective. Meriania may release nectar through the anther connective, but has additional nectary stomata on the inner walls of the hypanthium. Miconia has nectary stomata on the ovary apex. Charianthus nectaries were not found, but there is circumstantial evidence that nectar release occurs through the epidermis at the apex of the ovary and the lower portions of the inner wall of the hypanthium.

Conclusions

Nectar release in Melastomataceae is apparently related to nectary stomata and not filament slits. The presence of nectary stomata on stamens and on ovary apices in different lineages suggests that the acquisition of nectaries is a derived condition. Nectary location also supports a derived condition, because location is strongly consistent within each genus, but differs between genera.Key words: Blakea, Brachyotum, Charianthus, Huilaea, Meriania, Melastomataceae, Miconia, nectaries, nectary stomata, pollination     

Seed structure and the taxonomy of the Cruciferae

The external morphology and anatomy of the seeds of some 90 genera and some 200 species of the Cruciferae have been investigated. Emphasis has been laid on the relationships of seed structure to taxonomy. As regards seed anatomy, the testa is probably of greatest value in determining taxonomic relationships. Seed structure supports the Cruciferae as a natural taxon. In the present investigation, few genera and species show seed characters which are either exclusive or very distinct. Of the remainder, most genera are distinguishable from each other on a permutation of their macroscopic and microscopic seed characters. However it is difficult or impossible to distinguish between some genera on seed characters. The present investigation provides no support for tribal divisions within the Cruciferae.     

Pollen morphology of the subfamily Aurantioideae (Rutaceae)

The Aurantioideae is one of seven subfamilies of the Rutaceae consisting of two tribes, the Clauseneae, containing five genera, and the Citreae, with 28 genera. Each tribe contains three subtribes. The pollen morphology of the subfamily Aurantioideae is described and illustrated for the first time based on light and scanning electron microscopy. Five pollen types have been recognised in the subfamily, based mainly on aperture number and exine ornamentation. The pollen grains show a high degree of intergeneric variation. Pollen grains of Clauseneae are 3-colporate, microstriate or microstriato-reticulate, whereas pollen grains of Citreae are almost always 4/5 colporate with exines varying from microperforate to coarsely reticulate. Congruence between pollen types and the currently accepted classification is discussed, as well as the systematic implications of pollen morphology for the subfamily.