Phylogeny of the core Malvales: evidence from ndhF sequence data

The monophyly of the group comprising the core malvalean families, Bombacaceae, Malvaceae, Sterculiaceae, and Tiliaceae, was recently confirmed by molecular studies, but the internal structure of this clade is poorly understood. In this study, we examined sequences of the chloroplast ndhF gene (aligned length 2226 bp) from 70 exemplars representing 35 of the 39 putative tribes of core Malvales. The monophyly of one traditional family, the Malvaceae, was supported in the trees resulting from these data, but the other three families, as traditionally circumscribed, are nonmonophyletic. In addition, the following relationships were well supported: (1) a clade, /Malvatheca, consisting of traditional Malvaceae and Bombacaceae (except some members of tribe Durioneae), plus Fremontodendron and Chiranthodendron, which are usually treated as Sterculiaceae; (2) a clade, /Malvadendrina, supported by a unique 21-bp (base pair) deletion and consisting of /Malvatheca, plus five additional subclades, including representatives of Sterculiaceae and Tiliaceae, and Durionieae; (3) a clade, /Byttneriina, with genera traditionally assigned to several tribes of Tiliaceae, plus exemplars of tribes Byttnerieae, Hermannieae, and Lasiopetaleae of Sterculiaceae. The most striking departures from traditional classifications are the following: Durio and relatives appear to be more closely related to Helicteres and Reevesia (Sterculiaceae) than to Bombacaceae; several genera traditionally considered as Bombacaceae (Camptostemon, Matisia, Phragmotheca, and Quararibea) or Sterculiaceae (Chiranthodendron and Fremontodendron) appear as sister lineages to the traditional Malvaceae; the traditional tribe Helictereae (Sterculiaceae) is polyphyletic; and Sterculiaceae and Tiliaceae, as traditionally circumscribed, represent polyphyletic groups that cannot sensibly be maintained with their traditional limits for purposes of classification. We discuss morphological characters and conclude that there has been extensive homoplasy in characters previously used to delineate major taxonomic groups in core Malvales. The topologies here also suggest that /Malvatheca do not have as a synapormophy monothecate anthers, as has been previously supposed but, instead, may be united by dithecate, transversely septate (polysporangiate) anthers, as found in basal members of both /Bombacoideae and /Malvoideae. Thus, “monothecate” anthers may have been derived at least twice, independently, within the /Bombacoideae (core Bombacaceae) and /Malvoideae (traditional Malvaceae).     

Circumscription of the Malvales and relationships to other Rosidae: evidence from rbcL sequence data

The order Malvales remains poorly circumscribed, despite its seemingly indisputable core constituents: Bombacaceae, Malvaceae, Sterculiaceae, and Tiliaceae. We conducted a two-step parsimony analysis on 125 rbcL sequences to clarify the composition of Malvales, to determine the relationships of some controversial families, and to identify the placement of the Malvales within Rosidae. We sampled taxa that have been previously suggested to be within, or close to, Malvales (83 sequences), plus additional rosids (26 sequences) and nonrosid eudicots (16 sequences) to provide a broader framework for the analysis. The resulting trees strongly support the monophyly of the core malvalean families, listed above. In addition, these data serve to identify a broader group of taxa that are closely associated with the core families. This expanded malvalean clade is composed of four major subclades: (1) the core families (Bombacaceae, Malvaceae, Sterculiaceae, Tiliaceae); (2) Bixaceae, Cochlospermaceae, and Sphaerosepalaceae (Rhopalocarpaceae); (3) Thymelaeaceae sensu lato (s.l.); and (4) Cistaceae, Dipterocarpaceae s.l., Sarcolaenaceae (Chlaenaceae), and Muntingia. In addition, Neurada (Neuradaceae or Rosaceae) falls in the expanded malvalean clade but not clearly within any of the four major subclades. This expanded malvalean clade is sister to either the expanded capparalean clade of Rodman et al. or the sapindalean clade of Gadek et al. Members of Elaeocarpaceae, hypothesized by most authors as a sister group to the four core malvalean families, are shown to not fall close to these taxa. Also excluded as members of, or sister groups to, the expanded malvalean clade were the families Aextoxicaceae, Barbeyaceae, Cannabinaceae, Cecropiaceae, Dichapetalaceae, Elaeagnaceae, Euphorbiaceae s.l., Huaceae, Lecythidaceae, Moraceae s.l., Pandaceae, Plagiopteraceae, Rhamnaceae, Scytopetalaceae, Ulmaceae, and Urticaceae.     

广义锦葵科火绳树属4个种的枝条木材解剖及其分类学意义

研究了广义锦葵科火绳树属4个种枝条的木材解剖。火绳树属枝条为散孔至半环孔材,管孔主要为单管孔和2～3个管孔组成的径列复管孔;导管间纹孔式和射线导管间纹孔式互列、小;侵填体和螺纹加厚缺如。射线主要为单列射线,2～3列射线较多;射线细胞多为方形,射线组织主要为异型,边缘直立细胞常1行;射线组织稀为同型;鞘细胞和瓦形细胞缺如。轴向薄壁组织傍管和离管型,主要为带状。晶体丰富,主要在射线、纤维和薄壁组织中。研究的4个种可以通过枝条木材解剖特征加以区分。     

Historical biogeography and character evolution of Cistaceae (Malvales) based on analysis of plastid rbcL and trnL-trnF sequences

Cistaceae consist of eight genera and about 180 species. Some taxonomic limits and relationships within the family remain unresolved when relying exclusively on morphological data. In the present study, a phylogeny was reconstructed and divergence times were estimated for 47 species representing various groups in Cistaceae and using coding (rbcL) and spacer (trnL-trnF) sequences of plastid DNA. The firm set of morphological synapomorphies that indicates the monophyly of the family is supported by both Bayesian and parsimony analyses. Five major lineages can be distinguished within the Cistaceae: (1) an early-diverging lineage containing Fumana species; (2) the New World Lechea clade; (3) the Helianthemum s.l. clade, containing two sister groups, one of species from the New World (Crocanthemum, Hudsonia) and the other with species from the Old World (Helianthemum s. str.); (4) the Tuberaria clade; and (5) a cohesive complex consisting of Halimium and Cistus species. Evolutionary shifts in 12 key characters of Cistaceae are inferred based on the most plausible phylogenetic hypothesis. Reconstructing the evolution of ovule position supports anatropous ovules as the ancestral condition within the Cistaceae, which is currently found only in Fumana. The Cistus-Halimium assemblage is consistently obtained as a natural clade and further supported by a cytological synapomorphy (chromosome number n=9). Optimisation of ancestral distribution areas and estimates of divergence times reveal an early divergence (10.17-18.51 Ma) of the Mediterranean-European genera, which may be related to subtropical vegetation, as complemented by paleobotanical data. In addition, the occurrence of multiple, independent migration events from the Old World to America between the Middle Miocene (8.44-14.7 Ma; Lechea) and the Upper Miocene (5.15-9.20 Ma; Crocanthemum/Hudsonia), and to the Canary Islands in the Pleistocene is inferred. We argue that the Mediterranean basin has been the main centre of differentiation of Cistaceae.     

Comparative floral structure and systematics in Apodanthaceae (Rafflesiales)

Comparative studies on floral morphology, anatomy, and histology were performed to identify shared features of the genera of Apodanthaceae (Rafflesiales): Apodanthes, Pilostyles, and Berlinianche. Berlinianche was studied for the first time in detail and its affinity to Apodanthaceae was confirmed. It has a previously undescribed hair cushion on the inner perianth organs and inaperturate pollen. Shared features of members of Apodanthaceae are: unisexual flowers; three (or four) alternating di-/tetra- or tri-/hexamerous whorls of scales of which the inner one or two correspond to a perianth; a synandrium with pollen sacs typically arranged in two rings; opening by a dehiscence line between the two rings of pollen sacs; large vesicular hairs above the synandrium; a gynoecium with four united carpels; inferior and unilocular ovaries with four parietal placentae, ovules tenuinucellate, anatropous with two well developed integuments, oriented in various directions; a nectary disk. Apodanthaceae share some special structural features with Malvales.     

The systematic relationships of glucosinolate-producing plants and related families: a cladistic investigation based on morphological and molecular characters

A cladistic analysis is performed using 94 morphological and biochemical characters for 42 genera to compare a phylogeny based on morphological data with those obtained using different genes ( rbc L, atp B, 18S RNA, mat K) or their combination with morphological data, and to understand the floral evolution within the expanded Brassicales (Capparales) relative to Sapindales and Malvales. The tree produced with morphological data is congruent with those obtained from macromolecular studies in obtaining a well-supported glucosinolate-producing clade and an expanded Sapindales. The combined analysis of the morphological and molecular characters is generally well resolved with support for many of the relationships. The inclusion of the fossil taxon Dressiantha demonstrates the value of inserting fossil evidence in phylogenetic analyses. However, the fossil appears to be related to the Anacardiaceae and not to the Brassicales. The core Brassicales are well supported by a number of synapomorphies, although the internal position of Tovariaceae and Pentadiplandraceae is not well resolved. Emblingiaceae appears to be related to Bataceae and Salvadoraceae. Several significant morphological characters are mapped on the combined trees and their evolutionary significance is discussed. Within Brassicales and Sapindales several well supported clades can be recognized which merit ordinal or subordinal status, putting the present orders at a higher level; these include: Tropaeolales, Setchellanthales, Batidales, Brassicales (Brassiciflorae), Burserales, Sapindales and Rutales (Sapindiflorae). The present scheme of affinities within the Brassicales corresponds well with a gradual morphological evolution in the order.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 453–494.     

瓦形细胞在广义锦葵科中的分布及其系统学意义

基于文献和作者的研究,该文讨论了瓦形细胞的识别、类型、变异及在广义锦葵科中的分布及其系统学意义。瓦形细胞是一种特殊射线细胞,呈不定的横列,常分散在横卧细胞之间,常无细胞内含物,其宽度远比横卧细胞为小,根据瓦形细胞与横卧细胞高度、宽度的相对大小,分为榴莲型、中间型和翅子树型3种类型,目前为止仅在广义锦葵科9个亚科中的7亚科39个现存属和5个化石属中发现;榴莲型、翅子树型和中间型瓦形细胞分别在22、20和5个属中发现,具有中间型的属同时具有榴莲型或/和翅子树型。仅翅子树型和中间型瓦形细胞在化石中发现,榴莲型可能比翅子树型古老。瓦形细胞在广义锦葵科中的分布,对研究一些类群的系统发育有意义。     

Petenaeaceae,a new angiosperm family in Huerteales with a distant relationship to Gerrardina (Gerrardinaceae)

Petenaea cordata (from northern Central America) was first described in Elaeocarpaceae and later placed in Tiliaceae, but most authors have been uncertain about its familial affinities. It was considered a taxon incertae sedis in the Angiosperm Phylogeny Group classification (APG III). A recent collection was made in Guatemala, and analysis of both rbcL and atpB in the large Soltis et al. angiosperm matrix, the most completely sampled study published to date, indicated a moderately supported relationship to Tapiscia (Tapisciaceae, the only member of the newly recognized order Huerteales in this matrix; 81% bootstrap support). We then conducted a more restricted analysis using the Bayer et al. rbcL/atpB matrix for Malvales supplemented with the other genera of Huerteales from published studies. Our results indicate a distant, weakly supported sister‐group relationship to the African genus Gerrardina (Gerrardinaceae; Huerteales). After comparison of the characters cited in the literature and an examination of herbarium material of both genera, we could find no obvious synapomorphies for Gerrardina and Petenaea or any other relationship of the latter, and we therefore propose the new monogeneric family, Petenaeaceae. The polymorphic order Huerteales now comprises four small families: Dipentodontaceae, Gerrardinaceae, Petenaeaceae and Tapisciaceae. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 16–25.     

Structure and evolution of the androecium in the Malvatheca clade (Malvaceae s.l.) and implications for Malvaceae and Malvales

Androecial development and structure as well as floral vasculature of six selected species of Bombacoideae and of several smaller lineages of the Malvatheca clade (Malvaceae s.l.) were studied. All studied taxa share a similar pattern of androecial development: initially, five antepetalous/antetepalous and five alternipetalous/alternitepalous primary androecial primordia develop on a ring wall. Two elongate secondary androecial primordia form on each antepetalous/antetepalous sector. At anthesis the androecium consists of an androecial tube crowned by five androecial lobes. Each of these lobes is the developmental product of an alternipetalous/alternitepalous primary androecial primordium and its two neighbouring antepetalous/antetepalous secondary androecial primordia. The elongate, sessile androecial units are positioned along the lateral margins of the androecial lobes and in the distal part of the androecial tube. Seen in the light of the most recent studies of floral development and phylogeny of the Malvaceae and the Malvales as a whole, our data indicate that i) elongate, sessile androecial units are ancestral in the Malvatheca clade, that ii) an obdiplostemonous floral ground plan is a synapomorphy for the Malvaceae, and that iii) diplostemony is most likely ancestral in the Malvales.     

蚬木的大孢子发生与胚囊发育兼论蚬木属的系统亲缘

蚬木Excentrodendron hsienmu雌雄花在发育早期均有小孢子和大孢子的早期发育, 难以区分。蚬木子房5室, 具中轴胎座, 每室2胚珠; 胚珠倒生, 厚珠心, 双珠被, 成熟胚囊内珠被3层细胞, 外珠被3-4层细胞, 内外珠被共同形成之字形珠孔; 单细胞孢原, 大孢子四分体主要为线形, 稀为T形, 通常合点端大孢子为功能大孢子, 胚囊为蓼型; 在大孢子发生和胚囊发育时期有退化现象, 成熟胚囊时期退化率和种子退化率分别达88%和91%。蚬木属Excentrodendron在内外珠被层数上与柄翅果属Burretiodendron明显不同, 也与翅子树属Pterospermum、非洲芙蓉族Dombeyeae不同。蚬木属与柄翅果属的分离一直没有得到广泛接受, 但胚胎学证据支持蚬木属的建立; 与广义锦葵科Malvaceae s.l.其他属胚胎学资料的比较表明, 蚬木属在广义锦葵科中较孤立。