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.     

The Floral Biology of Tricyrtis affinis Makino (Liliaceae)

Abstract The floral biology of Tricyrtis affinis was investigated and compared with that of four species of Tricyrtis which had been reported by the author. The flower opens for two days and is protandrous as in T. latifolia, T. flava , and T. ohsumiensis. The primary pollinators of T. affinis were Bombus diversus diversus and Amegilla sp., which were not different from those of the previous species although the shape and the color of the T. affinis flower are somewhat different from the others. The whole perianth of T. affinis absorbs UV light fairly well, and the large purple spotted area near the base absorbs it markedly well. The UV absorption pattern of the T. affinis flower is similar to that of T. latifolia. T. affinis is also self-compatible, like the others, and seeds obtained by self-pollination germinated well. Pollination of T. affinis is characterized by a refined system.     

Self-pollination of Asarum caulescens Maxim. (Aristolochiaceae) in Japan

Abstract Observations in two populations of Asarum caulescens belonging to sect. Asarum indicate that inbreeding predominates becuase (1) no effective pollinator was observed, (2) bagged flowers set fruits with well-swollen seeds, and (3) the behaviour of filaments, changing from recurved to straight posture, results in direct deposition of pollen grains on the stigmas. This result agrees with reports on three other species of sect. Asarum in Europe and North America. We suggest that species of sect. Asarum diverged from an autogamous ancestor.     

Molecular phylogeny and taxonomic implications of Asarum (Aristolochiaceae) based on ITS and matK sequences

The genus Asarum (Aristolochiaceae) encompasses approximately 120 species from five sections. Taxonomic controversies concerning the genus Asarum and/or its intrageneric classification remain unresolved. In particular, sect. Heterotropa accounts for a large percentage of the genus (80 of 120 species) and is well diverged in the Sino–Japanese Forest subkingdom. Reconstruction of Heterotropa phylogeny and estimation of its divergence times would provide significant insight into the process of species diversity in the Sino–Japanese floristic region. This study encompassed 106 operational taxonomic units (OTUs), and phylogenetic analyses were conducted based on internal transcribed spacer (ITS) and matK sequences. Although the matK sequences provided informative results solely for section Geotaenium, phylogenetic trees based on ITS regions yielded a clear result for several sections. Three sections, Asarum, Geotaenium and Asiasarum, were supported as robust monophyletic groups, whereas Heterotropa had low support. Sect. Hexastylis was revealed to be polyphyletic, suggesting taxonomic reconstruction would be needed. Sect. Heterotropa comprises two clades, which correspond to species distribution ranges: mainland China and the island arc from Taiwan to mainland Japan via the Ryukyu Islands. It is notable that the common ancestry of the latter clade in the eastern Asian islands was highly supported, suggesting that the present species diversity of Heterotropa was initially caused by allopatric range fragmentation in East Asia.     

兰花花发育的分子生物学研究进展

兰科植物是开花植物中最大的家族之一,其花高度进化,具有花瓣状的萼片,特化的唇瓣和雌雄蕊合生的蕊柱,是单子叶植物花发育生物学研究的理想材料。近年来有关兰花花发育基因调控的研究已取得了一些进展,本文从兰花开花转换和兰花花器官的形成两方面综述了近年来国内外关于兰花花发育分子机理方面的研究进展,主要介绍了文心兰、蝴蝶兰和石斛兰的花发育相关基因,并推测了兰花花被的进化发育过程,认为兰花的DEFICIENS(DEF)类基因在早期经过两轮复制,形成了四类DEF基因,从而促进了花萼与花瓣的分离、侧瓣与唇瓣的分离。该文最后对今后兰花花发育研究的发展方向进行了展望。     

Floral biology and histochemical analysis of Vanilla edwallii Hoehne (Orchidaceae: Vanilloideae): an orchid pollinated by Epicharis (Apidae: Centridini)

The genus Vanilla is the most diverse in Vanilloideae, with ca 90 species distributed among tropical regions. Despite their economic importance, studies on pollination of Vanilla are very scarce and data on pollinators of species endemic to Brazil are lacking. Based on fieldwork and laboratory investigations, the floral biology of V. edwallii was studied. The pollinators and pollination process were recorded at the Serra do Japi reserve, state of São Paulo, southeastern Brazil, and the presence of floral reward was also investigated. Vanilla edwallii blooms in summer. The lateral inflorescences produce up to four pale green flowers. The white labellum is united to the base of the column forming a mentum. In the studied population V. edwallii is pollinated by Epicharis (Hoplepicharis) affinis, where the males exhibit a territorial behavior, defending flowers from other possible flower visitors. The pollen is deposited on the scutellum of bees when they abandon the flower. The mentum region is dry, suggesting no nectar production. The only secretory structures are osmophores dispersed on the inner surface of the lip responsible for production of a sweet fragrance, which together with color and morphology of flowers is related to bee attraction. The labellum is rich in mucilaginous cells, while the mucilaginous substance is retained inside the cells. The histochemical analysis also detected the presence of phenolic compounds and starch concentrated mainly at the adaxial surface of the lip and around the vascular bundles.     

重庆特有濒危植物缙云黄芩的繁育系统研究

缙云黄芩（Scutellaria tsinyunensis）为重庆市缙云山特有分布种,目前已经处于濒危状态。本文在定点观测的基础上,运用过氧化氢检测法、花粉-胚珠比（P/O）和套袋实验等方法对缙云黄芩的开花特征和繁育系统进行了分析。结果表明：缙云黄芩花展示和花设计具有适合蜂类等传粉昆虫的传粉综合征,熊蜂(Bombus)和食芽蝇为主要的访花者,P/O为7 618±390,繁育系统为专性异交,传粉套袋实验也证实其必需传粉者异花传粉且可能自交不亲和;其雌雄蕊紧靠的花部结构及花粉活力和柱头可授性低、昆虫的访花频率较低等内外因素致使其自然坐果率较低(20.08%)且结实少(5.6个/株)。由于缙云黄芩小坚果萌发率较低,其有性生殖能力较低,居群扩大困难,应尽快采用人工栽培助其复壮等保护措施。     

A new species of Aristolochia (Aristolochiaceae) from Thailand

Aristolochia dinghoui is described from southwestern Thailand. It is morphologically similar toA. harmandiana Pierre ex Lecomte, from Cambodia and Laos, and also bears some resemblance toA. philippinensis Warb. andA. sericea Blanco, both from the Philippines. A key to these four species is included, and some of their diagnostic features are listed.

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Resumen   Aristolochia dinghoui est décrite à partir de spécimens recueillis dans le sud-buest de la Thailande. Morphologiquement pareille à l'A. harmandiana Pierre ex Lecomte de l'Indochine, elle présente également des ressemblances avecA. philippinensis Warb. etA. sericea Blanco, des iles Philippines. Une clé est proposée pour distinguer ces quatre espèces. Les caractères diagnostiques de l'{btA. dinghoui} sont illustrés.

     

Chromosome number ofSaruma oliver (Aristolochiaceae)

Chromosome number ofSaruma henryi, the only species of the genus, was counted for the first time. The species has 2n=52 chromosomes, and its chromosomal complement is characteristically composed of very small chromosomes. Based on chromosome data available for the family, comparisons indicate an isolated position ofSaruma in Aristolochiaceae.     

Floral morphogenesis in Euptelea (Eupteleaceae, Ranunculales)

BACKGROUND AND AIMS: Based on molecular phylogenetic studies, the unigeneric family Eupteleaceae has a prominent phylogenetic position at or near the base of Ranunculales, which, in turn, appear at the base of eudicots. The aim of the present paper is to reveal developmental features of the flowers and to put the genus in a morphological context with other basal eudicots. METHODS: Flowers in all developmental stages of Euptelea pleiosperma were collected in the wild at intervals of 7-10 d in the critical stages and studied with a scanning electron microscope. KEY RESULTS: Remnants of a perianth are lacking throughout flower development. Floral symmetry changes from monosymmetric to asymmetric to disymmetric during development. Asymmetry is expressed in that the sequence of stamen initiation is from the centre to both lateral sides on the adaxial side of the flower but starting from one lateral side and proceeding to the other on the abaxial side. Despite the pronounced floral disymmetry, a dimerous pattern of floral organs was not found. The carpel primordia arise between the already large stamens and alternate with them. Stamens and carpels each form a somewhat irregular whorl. The carpels are ascidiate from the beginning. The stigma differentiates as two crests along the ventral slit of the ovary. The few lateral ovules alternate with each other. CONCLUSIONS: Although the flowers have some unusual autapomorphies (wind pollination, lack of a perianth, pronounced disymmetry of the floral base, long connective protrusion, long temporal gap between androecium and gynoecium initiation, small space for carpel initiation), they show some plesiomorphies at the level of basal eudicots (free carpels, basifixed anthers, whorled phyllotaxis), and thus fit well in Ranunculales.     

滇鼠刺花的形态发生（鼠刺科）

在扫描电镜下 ,观察了滇鼠刺 (IteayunnanensisFranch .)花的形态发生。花 3朵一束 ,排成总状花序。花器官为轮状结构 ,向心发生 ;花萼以 2 /5螺旋式相继发生 ,5个花瓣原基几乎同步地在花萼内侧与其互生的位置发生。雄蕊单轮对萼。当雄蕊发生后 ,花顶中心的分生组织开始凹陷 ,成为浅锅状 ;在其周围出现一个环状的分生组织 ,随之 ,2心皮原基产生 ,进而发育为马蹄形。初期的心皮相互分离 ,随着进一步发育 ,心皮内卷 ,彼此靠近、紧贴 ,逐渐于腹面合生 ,形成 2室的中轴胎座 ;花柱的腹维管束通过薄壁组织连通 ;花期柱头融合 ,因此该种为合生心皮。对鼠刺属 (Itea)及相关类群花发育性状和花结构进行了比较 ,支持把鼠刺属提升为鼠刺科 (Iteaceae)的观点。     

Reproductive Biology of the Distylous Manettia luteo-rubra (Rubiaceae)

The reproductive biology of Manettia luteo-rubra was studied in the coastal montane Atlantic rain forest of southeastern Brazil. This Rubiaceae is a perennial vine that flowers all the year round, but has a flowering peak during the dry season. It presents reciprocal herkogamy, thus the plants are morphologically distylous. The morphs occur in a 1:1 ratio, and pollen diameter and corolla length vary between short and long-styled flowers. Manettia luteo-rubra displays typical heterostylous self-incompatibility and sets almost no fruits from self- or intramorph pollinations. The flowers are tubular, red with yellow lobes, and odourless. Anthesis is asynchronous, and the flowers last about four days. Concentration of sugars in nectar is similar in both morphs, ca. 24%, this concentration being typical for hummingbird flowers. Three species of hummingbirds are the major pollinators of the flowers of M. luteo-rubra at the study site: the hermits Phaethornis eurynome and P. squalidus, and the trochiline Thalurania glaucopis. Three species of Heliconius butterflies act as minor pollinators. Both morphs of M. luteo-rubra exhibit natural fruit-set of about 80%, this reproductive output being maintained throughout the year by the pollinators' constancy to the flowers.     

商陆属植物的花器官发生

为进一步研究商陆科的系统位置提供花器官发生和发育的证据,在扫描电子显微镜下观察了商陆Phytolacca acinosa、多雄蕊商陆P. polyandra和垂序商陆P. americana的花器官发生.结果表明: 商陆属植物花被的发生均为2/5型螺旋发生.在同一个种不同的花蕾中,花被的发生有两种顺序:逆时针方向和顺时针方向.远轴侧非正中位的1枚先发生.雄蕊发生于环状分生组织.在单轮雄蕊的种中8-10枚雄蕊为近同时发生;两轮雄蕊的种8枚内轮雄蕊先发生,6-8枚外轮雄蕊随后发生,内轮雄蕊为同时发生,外轮雄蕊发生次序不规则.心皮原基也发生于环状分生组织,8-10枚心皮原基为同时发生.在后来的发育过程中,商陆的心皮发育成近离生心皮雌蕊;其他2种心皮侧壁联合发育成合生心皮雌蕊.对商陆属植物花器官发生的类型及发育形态学做了分析,结果支持商陆科在石竹目系统发育中处于原始地位的观点.     

Chaotic Floral Phyllotaxis and Reduced Perianth in Achlys (Berberidaceae)

Among the 16 genera of the Berberidaceae Achlys is the only one with a reduced perianth, an irregular floral phyllotaxis, and variable stamen number. Early floral stages show an unstable (chaotic) arrangement of the organ primordia. Only the single carpel of the gynoecium has a more fixed position in that the placenta is formed in the adaxial half of the flower. The irregularities in the androecium may be caused by the lack of influence of a perianth on floral symmetry. On the other hand, the regular orientation of the carpel is perhaps due to the early polarity of the flower, whereby the abaxial half of the flower is larger (with further developed stamen primordia) at the time when carpel polarity is established.     

滇鼠刺花的形态发生(鼠刺科)

在扫描电镜下,观察了滇鼠刺(Itea yunnanensis Franch.)花的形态发生.花3朵一束,排成总状花序.花器官为轮状结构,向心发生;花萼以2/5螺旋式相继发生,5个花瓣原基几乎同步地在花萼内侧与其互生的位置发生.雄蕊单轮对萼.当雄蕊发生后,花顶中心的分生组织开始凹陷,成为浅锅状;在其周围出现一个环状的分生组织,随之,2心皮原基产生,进而发育为马蹄形.初期的心皮相互分离,随着进一步发育,心皮内卷,彼此靠近、紧贴,逐渐于腹面合生,形成2室的中轴胎座;花柱的腹维管束通过薄壁组织连通;花期柱头融合,因此该种为合生心皮.对鼠刺属(Itea)及相关类群花发育性状和花结构进行了比较,支持把鼠刺属提升为鼠刺科(Iteaceae)的观点.     

Two new species of Aristolochia (Aristolochiaceae) from Brazil and Peru

Aristolochia dalyi, from western Peruvian and Brazilian Amazonia, andA. bahiensis, from Bahia, Brazil, are described and illustrated. The species belong toAristolochia ser.Thyrsicae andA. ser.Hexandrae subser.Anthocaulicae, respectively. A key to the eight western Amazonian species of the seriesThyrsicae is presented.Aristolochia dalyi closely resemblesA. silvatica Barb. Rodr. from the Río Negro basin, andA. bahiensis—the first cauliflorous species ofAristolochia known from the Mata Atlantica—is similar toA. guentheri O. C. Schmidt andA. klugii O. C. Schmidt, from the Western Amazon basin. Characters based primarily on the perianth shape, along with some vegetative features, are used to distinguish the two newly described species from their close relatives.

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Resumen   Aristolochia dalyi, del occidente de la amazonía peruana y brasilera, yA. bahiensis, del estado de Acre, en Brasil, son descritas e ilustradas. Las especies pertenecen aAristolochia ser.Thyrsicae yA. ser.Hexandrae subser.Anthocaulicae respectivamente.Aristolochia dalyi es incluída en una clave para diferenciarla de las especies de la serieThyrsicae presentes en la Amazonía occidental, y resulta ser similar aA. silvatica Barb. Rodr, propia de la cuenca del río Negro; por su parte,A. bahiensis, hasta ahora la única especie deAristolochia cauliflora hallada en la Mata Atlántica, es similar aA. guentheri O. C. Schmidt yA. klugii O. C. Schmidt, propias del occidente de la cuenca amazónica. Los caracteres diagnósticos de las nuevas especies se basan principlalmente en la forma del perianto, aunque algunas diferencias vegetativas son también reconocidas.