Pollen diversity in Aquifoliales

Aquifoliales, as currently circumscribed, comprise five families and 20 genera, most of which have not been compared with regard to their pollen. Generic relationships within the order have not been fully resolved with molecular data, but pollen can provide a potential source of characters for future phylogenetic studies. To assess diversity in the order, pollen from 19 genera was examined with light and scanning electron microscopy. Pollen is typically tricolpate to triporate, although grains with one to nine pores were observed. Grains are small to medium, with a polar axis of 6–44 μm and an equatorial axis of 10–47 μm. Irregular pollen was recorded from nine genera. Exine patterning is diverse at the generic level and includes psilate, microechinate, striate to reticulate and clavate types, and is quite complex in some genera. All but four genera of Aquifoliales can be readily distinguished by their pollen, if heavy deposits of pollenkitt (present in 11 genera) are removed during and after acetolysis. Pollen from multiple taxa of Gomphandra, the second most diverse genus in the order, was surveyed to investigate species boundaries. Specimens of Gomphandra from continental Asia exhibited seven different pollen morphologies, suggesting that exine patterns may be useful for the recognition of species in that region. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 169–190.     

Multicarpellate gynoecia in angiosperms: occurrence,development, organization and architectural constraints

Most angiosperms have gynoecia with two to five carpels. However, more than five carpels (here termed ‘multicarpellate condition’) are present in some representatives of all larger subclades of angiosperms. In such multicarpellate gynoecia, the carpels are in either one or more than one whorl (or series). I focus especially on gynoecia in which the carpels are in a single whorl (or series). In such multicarpellate syncarpous gynoecia, the closure in the centre of the gynoecium is imprecise as a result of slightly irregular development of the carpel flanks. Irregular bumps appear to stuff the remaining holes. In multicarpellate gynoecia, the centre of the remaining floral apex is not involved in carpel morphogenesis, so that this unspent part of the floral apex remains morphologically undifferentiated. It usually becomes enclosed within the gynoecium, but, in some cases, remains exposed and may or may not form simple excrescences. The area within the remaining floral apex is histologically characterized by a parenchyma of simple longitudinal cell rows. In highly multicarpellate gynoecia with the carpels in a whorl, the whorl tends to be deformed into an H‐shaped or star‐shaped structure by differential growth of the floral sectors, so that carpels become aligned in parallel rows, in which they face each other with the ventral sides. In this way, a fractionated compitum may still be functional. Multicarpellate gynoecia (with the carpels in one whorl or series) occur in at least one species in 37 of the 63 angiosperm orders. In contrast, non‐multicarpellate gynoecia are present in at least one species of all 63 orders. The basal condition in angiosperms is more likely non‐multicarpellate. Multicarpellate gynoecia are restricted to flowers that are not highly synorganized. In groups with synorganized androecium and gynoecium and in groups with elaborate monosymmetric flowers, multicarpellate gynoecia are lacking. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 1–43.     

Palm snorkelling: leaf bases as aeration structures in the mangrove palm (Nypa fruticans)

Mangrove species have evolved specialized structures, such as pneumatophores, to supply oxygen to the roots, but, in Nypa fruticans, the only mangrove palm, no such structure has been reported. This study aimed to determine the adaptations of N. fruticans to the mangal habitat with special reference to the air‐supplying structure. Following senescence, the rachis is abscised at the zone of junction with the leaf base. Simultaneously, lenticels develop so that, when abscission is completed, a network of mature lenticels covers the leaf base. Expansigenous aerenchyma with increasing porosity towards the stem junction occurs in the leaf base. The first two root branching orders present a subero‐lignified rhizodermis and exodermis, and the cortex consists of schizo‐lysigenous aerenchyma with wide lacuna, limiting radial oxygen loss and facilitating longitudinal oxygen transport to living tissues. Lifespan estimation suggests that leaf bases can live for up to 4 years following abscission, ensuring the persistence of aeration structures. This study provides structural evidence indicating that N. fruticans has evolved a unique type of air‐supplying structure in the mangal habitat. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 257–270.     

What is the subtribe Glossonematinae (Apocynaceae: Asclepiadoideae)? A phylogenetic study based on cpDNA spacer

Evidence from the chloroplast trn T-L spacer, trn L intron and trn L-F spacer shows the subtribe Glossonematinae of the tribe Asclepiadeae, hitherto composed of the Arabian and North African genera Glossonema , Odontanthera and Solenostemma , not to be monophyletic. While the affinities of Solenostemma cannot be determined with certainty at present, molecular, karyological and morphological evidence suggests that Glossonema and Odontanthera are closely allied to Pentarrhinum , an African genus of five species, belonging to the Cynanchinae.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 145–158.     

The questionable affinities of Corsia (Corsiaceae): evidence from floral anatomy and pollen morphology

The floral anatomy and pollen morphology of Corsia are described in the context of its systematic relationships. Flowers of Corsia are epigynous, lack septal nectaries and possess a large labellum formed from the outer median tepal (sepal). The labellum is highly vascularized and has a prominent outgrowth (callus) that is apparently nectiiferous in some species of section Sessilis , although not in section Unguiculatis . The six fertile stamens are proximally fused to the style, forming a gynostemium. This combination of labellum and gynostemium is otherwise found only in Orchidaceae (Asparagales), but the orchid labellum is formed from the opposite median inner tepal, and is therefore not homologous with that of Corsia . The three genera of Corsiaceae ( Corsia , Arachnitis and Corsiopsis ) are markedly different in some respects; e.g. only Corsia has a gynostemium. However, they share a unique synapomorphy in the presence of a labellum formed from the outer median tepal (sepal). Corsia and Arachnitis are also similar in pollen sexine sculpturing. Among other putative relatives, the range of morphological similarities between Corsia and Campynemataceae (Liliales) tends to support recent preliminary inferences from molecular data that they are closely related, but a relationship with Thismia (Dioscoreales) cannot be discounted. Both Campynemataceae and Thismia share similarities with Corsia , including epigyny, absence of septal nectaries, presence of tepal nectaries, and pollen morphology. © 2002 Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 315–324.     

Leaf and stem anatomy of Vochysiaceae in relation to subfamilial and suprafamilial systematics

Several leaf anatomical features are potentially systematically informative within both the family Vochysiaceae and the order Myrtales, notably tracheoidal idioblasts, mucilage cells and secretory canals. Tracheoids with spiral wall thickenings are present in the mesophyll of most species of Vochysia , and also occur in several other families of Myrtales. Mucilage cells are common in the leaf epidermis in some Vochysiaceae. Secretory ducts are present in the midrib in Salvertia and Vochysia , which are apparently closely related, although Salvertia also shares some leaf anatomical characters with Qualea and Callisthene . Anatomical data do not support the segregation of Ruizterania from Qualea ; leaves of R. albiflora leaves are very similar to those of Q. paraensis in venation pattern, and leaf and stem anatomy. Different venation patterns are characteristic of sections within the genus Qualea , but within the large genus Vochysia , leaf anatomy is variable even within a subsection. Amongst other Myrtales, leaf anatomy of Vochysiaceae most closely resembles that of Combretaceae and Onagraceae. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 339–364.     

Gynoecium diversity and systematics in basal monocots

Gynoecium and ovule structure was comparatively studied in representatives of the basal monocots, including Acorales (Acoraceae), Alismatales (Araceae, Alismataceae, Aponogetonaceae, Butomaceae, Hydrocharitaceae, Junc‐aginaceae, Limnocharitaceae, Potamogetonaceae, Scheuchzeriaceae, Tofieldiaceae), Dioscoreales (Dioscoreaceae, Taccaceae), and Triuridaceae as a family of uncertain position in monocots. In all taxa studied the carpels or gynoecia are closed at anthesis. This closure is attained in different ways: (1) by secretion without postgenital fusion (Araceae, Hydrocharitaceae); (2) by partly postgenitally fused periphery but with a completely unfused canal (Alismataceae, Aponogetonaceae, Butomaceae, Limnocharitaceae, Scheuchzeriaceae, Dioscoreaceae, Taccaceae); (3) by completely postgenitally fused periphery but with an unfused canal in the centre (Acoraceae, Tofieldiaceae); (4) by complete postgenital fusion and without an (unfused) canal (Juncaginaceae, Potamogetonaceae). In many Alismatales (but without Araceae) carpels have two lateral lobes. The stigmatic surface is restricted to the uppermost part of the ventral slit (if the carpel is plicate); it is never distinctly double‐crested (Butomaceae?). Stigmas are commonly unicellular‐papillate and secretory in most taxa. The locules are filled with a (often) mucilaginous secretion in a number of taxa. Superficial (probably intrusive) ethereal oil cells were found in the carpel wall of Acorus gramineus (as in Piperales!). Idioblasts in carpels are otherwise rare. A number of basal monocots has orthotropous ovules, which is perhaps the plesiomorphic condition in the group. The presence of almost tenuinucellar (pseudocrassinucellar) ovules is relatively common (Acoraceae, many Araceae, some Alismatales s.s.), whereas completely tenuinucellar ovules are rare and do not characterize larger groups. However, crassinucellar ovules occur in the largest number of families among the study group (basal Araceae, many Alismatales s.s.) The outer integument is always annular in orthotropous ovules. The inner integument is often lobed and it mostly forms the micropyle, whereas the outer integument is always unlobed. Gynoecium structure supports the isolated position of Acoraceae as sister to all other monocots. However, in an overall view, if compared with all other families, Acoraceae clearly shows the greatest similarities with Araceae.     

A phylogenetic analysis of the monogenomic Triticeae (Poaceae) based on morphology

A cladistic analysis, primarily based on morphology, is presented from 40 diploid taxa representing the 24 monogenomic genera of the Triticeae. General problems related to the treatment of hybrids and supposedly allopolyploid heterogenomic taxa are highlighted. Special emphasis is given to taxa not traditionally included in Aegilops s.J. Most of the 33 characters used in the analysis are coded as binary. The only four multistate characters in the matrix are treated as unordered. Three diploid species of Bromus are used as outgroup. The number of equally parsimonious trees found is very large (approx. 170000; length = 107, ci = 0.36, ri = 0.75) and the strict consensus tree has an expectedly low level of resolution. However, most of the equally parsimonious trees owe their existence to an unresolved Aegilops clade. If this clade is replaced by its hypothetical ancestor, the number of equally parsimonious trees drops dramatically (48; length = 78, ci = 0.45, ri = 0.76). When trees for which more highly resolved compatible trees exist are excluded, only two trees remain. Bremer support is used as a measure of branch support. The trees based on morphology and on molecular data are largely incongruent.     

Three new species of Mitrephora (Annonaceae) from Sabah, Malaysia

Three new species of Mitrephora (Blume) Hook. f. & Thomson, M. clemensiorum, M. vittata and M. woodii , are described from Sabah, Malaysia. Mitrephora clemensiorum is related to M. korthalsiana Miq., but is distinguished by having long inflorescences, long flowering and fruiting pedicels, and fruits with sessile monocarps. Mitrephora vittata is related to M. reflexa Merr., but has lanceolate, subcoriaceous leaves, and densely pubescent inflorescence rachides, flowering pedicels and bracts. Mitrephora woodii is similar to M. heyneana (Hook. f. & Thomson) Thwaites, but has smaller flowers and fruits with sessile monocarps