Ovule,fruit and seed development in Abolboda (Xyridaceae,Poales): implications for taxonomy and phylogeny

Xyridaceae belongs to the xyrid clade of Poales, but the phylogenetic position of the xyrid families is only weakly supported. Xyridaceae is divided into two subfamilies and five genera, the relationships of which remain unclear. The development of the ovule, fruit and seed of Abolboda spp. was studied to identify characteristics of taxonomic and phylogenetic value. All of the studied species share anatropous, tenuinucellate and bitegmic ovules with a micropyle formed by the inner and outer integuments, megagametophyte development of the Polygonum type, seeds with a tanniferous hypostase, a helobial and starchy endosperm and an undifferentiated embryo, seed coat derived from both integuments with a tanniferous tegmen and a micropylar operculum, and fruits with a parenchymatous endocarp and mesocarp and a sclerenchymatous exocarp. Most of the ovule and seed characteristics described for Abolboda are also present in Xyris and may represent a pattern for the family. Abolboda is distinguished by the ovule type, endosperm formation and the number of layers in the seed coat, in agreement with its classification in Abolbodoideae. The following characteristics link Xyridaceae to Eriocaulaceae and Mayacaceae, supporting the xyrid clade: tenuinucellate, bitegmic ovules; seeds with a tanniferous hypostase, a starchy endosperm and an undifferentiated embryo; and a seed coat with a tanniferous tegmen. A micropylar operculum in the seeds of Abolboda is described for the first time here and may represent a synapomorphy for the xyrids. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 144–154.     

Seed and fruit anatomy ofCocculus hirsutus (Menispermaceae)

The ovules ofCocculus hirsutus are anatropous, bitegmic and, crassinucellate. The fruit is drupaceous, black purple, and laterally compressed and has a pericarp demarcated into exocarp and endocarp. The seeds are curved around the basal bodies. Testa and tegmen cells are thin-walled and unspecialized. In the ripe seed the inner epidermis of the tegmen persists, whereas the entire testa and the outer layer of the tegmen degenerate. Relationships of theMenispermaceae toRanunculaceae, Berberidaceae, andLardizabalaceae are supported.     

Seed Structure in Cannaceae: Taxonomic and Ecological Implications

The ovules and seeds of Canna show some striking differencesto those in other zingiberalean families. The pachychalazaldevelopment of the ovule results in a seed of which only a smallpart of the testa is of tegumentary origin. A silicified endotesta,characteristic of the order, is lacking. The mechanical layerof the seed is formed by a continuous exotesta of Malpighiancells. The intact seed coat is impermeable. The seed is ableto absorb water after the raising of a preformed imbibitionlid on the raphe. During imbibition the extotesta loses itshardness, allowing the embryo to emerge. The special structuralfeatures of the seed are discussed in relation to records onthe extreme longevity of Canna seeds. Canna tuerckheimii, C. jaegeriana, C. glauca, pachychalaza, Malpighian cells, imbibition lid, seed longevity     

Embryology and seed development of Syngonanthus caulescens (Poir.) Ruhland (Eriocaulaceae-Poales)

The embryology and the seed development of Syngonanthus caulescens are presented. This species possesses: a bithecous and tetrasporangiate anther, with a four-layered wall, a conspicuous endothecium of the baseplate type, a secretory tapetum formed by uninucleate cells, successive microsporogenesis resulting in isobilateral microspore tetrads, spiraperturate and binucleate pollen grains, an orthotropous, pendulous, bitegmic and tenuinucellate ovule, with a micropyle formed only by the inner integument, a megagametophyte of the Polygonum type, with formation of an antipodal cyst, free-nuclear and starchy endosperm, a broad and bell-shaped embryo, operculate and endotestal seeds, a seed coat derived from the inner layers of both integuments, and tanniniferous endotegmen. These embryological aspects are characteristic not only for Syngonanthus, but for the whole family, with few differences between genera. Furthermore, the pollen grain of the spiraperturate type and the cystic arrangement of the antipodals in the megagametophyte are peculiar and very distinctive features of Eriocaulaceae within the other Poales (commelinids).     

姜目芭蕉群植物种子解剖学研究及其系统学意义

研究了姜目芭蕉群代表植物象腿蕉属象腿蕉(Ensete glaucum)、旅人蕉属旅人蕉(Ravenala madagascariensis)与蝎尾蕉属Heliconia faranmansis?D6肿咏馄侍卣鳌＝峁砻鳎笸冉段藜僦制ぃ制し只霰砥ぁ⒑癖谧橹赴褪赴悖赴瞿谇邢虮谟刖断虮谠龊瘢缓系闱哂泻系闶矣牒系愣眩谥制ち恢榭浊兄榭琢旌涂赘堑姆只榭琢煳涡停赘侵挥赡谥制は赴钩桑褐榭浊制ぱ由煨纬芍制昵唬和馀呷?层细胞：内胚乳细胞径向延长,细胞内充满淀粉粒。旅人蕉具假种皮,种皮分化出外种皮、中种皮和内种皮,外种皮细胞纵向延长,中种皮为7-9层切向延长的薄壁细胞,内种皮为石细胞型：合点区无合点室,内种皮在此出现缺口,缺口为整体轮廓呈喇叭形的近等径薄壁细胞群填充;珠孔区无珠孔领与孔盖的分化：外胚乳缺,内胚乳发达。蝎尾蕉属的Heliconia faranmansis?D6肿游藜僦制ぃ制の薹只墒闾寤闲∏揖断蜓映げ⑴帕形だ缸吹谋”谙赴钩桑褐榭锥酥制は蛲庋由欤纬衫嗨平浦肿拥闹指纷唇峁梗何蘅赘怯胫榭琢斓哂杏晒ば纬傻挠不牵缓系闱肼萌私断嗨疲煌馀呷樵?-4层细胞,细胞壁波浪形弯曲,内胚乳发达。综合作者对兰花蕉(Orchidanha chinensis)和前人对芭蕉群的种子解剖学研究结果,初步总结了芭蕉群种子解剖学特征及其进化式样,讨论了姜目芭蕉群四科种子解剖学特征的系统分类学意义。     

Seed-coat anatomy of japanese species ofCorydalis andDicentra (Papaveraceae; Fumarioideae)

Development and structure of seed-coat were examined in 16 species ofCorydalis and two species ofDicentra. Neither the tegmen (developed ii) nor the testa (developed oi) is multiplicative during seed development. Mature seed-coat is consistent in all the species examined in having mechanical structure in the exo- or endotesta. Differences are found in (1) which of the integumentary layers develops into the main mechanical layer (exotesta or endotesta), (2) whether a mesotesta is differentiated or not, and (3) whether the endotegmen is persistent as a layer of thick-walled cells, is persistent only partially, or is thoroughly degenerated. Theses seed-coat characters distinguish six groups of species (i.e., four groups inCorydalis and two inDicentra), which represent well infrageneric taxa proposed on the other characters. Evidence from seed-coat anatomy further suggests thatDicentra spectabilis (subg.Hedycapnos) retains the primitive (endotestal) seed-coat of Fumarioideae.     

DEVELOPMENT OF NORMAL AND SEEDLESS ACHENES IN CICHORIUM INTYBUS (COMPOSITAE)

Cross- and partially cross-pollinated capitula of Cichorium intybus (Compositae, Lactuceae) were examined for a study of normal and seedless fruit development respectively. Embryos develop according to the Asterad pattern, and the free-nuclear endosperm becomes cellular 15–17 hrs after pollination. A zone of disorganized cellular material surrounds the embryo sac at anthesis, and, in normal achenes, this zone expands as the seed develops. Initially the developing seed elongates and comes into contact with the top of the ovary by 48 hrs. In contrast to this pattern, the ovule in developing seedless achenes degenerates within 72 hrs. Irregularities, such as an abnormally proliferating endothelium, embryo formation without endosperm, and endosperm formation without an embryo often accompany this degeneration. Differentiation of the pericarp in seeded achenes begins between 48 and 72 hrs, starting at the apex and proceeding basipetally; in seedless fruits the process is similar though initiated somewhat later. The normal pericarp at maturity exhibits a pigmented exocarp, a broad mesocarp of thick-walled lignified cells, and a tenuous endocarp. In seedless achenes the fruit coat is similar except that the exocarp is colorless and the cells of the mesocarp are relatively small.     

Embryology of <Emphasis Type="Italic">Petrosavia</Emphasis> (Petrosaviaceae,Petrosaviales): evidence for the distinctness of the family from other monocots

The affinities of Petrosavia, a rare, leafless, mycoheterotrophic genus composed of two species indigenous to East to Southeast Asia, have long been uncertain. However, recent molecular analyses show that the genus is sister to Japonolirion osense. Japonolirion and Petrosavia comprise the Petrosaviaceae, which are now placed in its own order, Petrosaviales, distinct from other monocots based on molecular analyses. We conducted an embryological study of Petrosavia, comparing it to Japonolirion, as well as to basal monocots (Acorus and Araceae) and more derived monocots (Nartheciaceae, Velloziaceae, and Triuridaceae). Our results showed that Petrosavia is very similar in embryology to Japonolirion, with both genera sharing a glandular anther tapetum, simultaneous cytokinesis in microspore mother cells, anatropous and crassinucellate ovules, T-shaped tetrads of megaspores, ab initio Cellular-type endosperm, and a mature seed coat composed of the exotesta, endotesta, and endotegmen. The two genera of Petrosaviaceae are clearly distinct from Acorus, and all Araceae, Nartheciaceae, Velloziaceae, and Triuridaceae genera in various combinations of characters. Thus, both molecular and embryological evidence support the distinctness of the Petrosaviaceae from other monocots and its placement in its own order, Petrosaviales.     

Embryology and Seed Development of Paepalanthus sect. Actinocephalus (Koern.) Ruhland (Eriocaulaceae)

Abstract: The embryology and seed structure of Paepalanthus sect. Actinocephalus species were studied. The embryological and structural seed characters fit well with those of the other commelinaceous families. Within the Commelinales sensu Dahlgren, Eriocaulaceae and Xyridaceae represent two embryologically close families. In Paepalanthus sect. Actinocephalus the ovule is orthotropus, bitegmic, and tenuicellate with a micropyle formed by the inner integument. The seeds are endotestal. The outer cell layer of the testa and the outer periclinal wall of the endotesta disintegrate during development. The endotegmen is tanniniferous. The outer layer of the tegmen becomes compressed and is no longer recognizable in the mature seed. The seeds are operculate.     

Taxonomic significance of pericarp and seed structure in Heeria argentea (Thunb.) Meisn. (Anacardiaceae) including reference to pachychalazy and recalcitrance

Heeria argentea (tribe Rhoeae), a monotypic, dioecious tree, is endemic to the core area of the Cape Floristic Region. The mature exocarp consists of a uniseriate layer of palisade-like epidermal cells, interspersed with modified stomata. The mature endocarp sensu stricto develops solely from the inner epidermis. It is essentially two-layered and resembles the state in Protorhus longifolia. This endocarp is here proposed as a distinct fourth endocarpal subtype under the so-called Anacardium -type. The large, pachychalazal, recalcitrant seed develops from the single, anatropous, bitegmic, crassinucellate ovule. This ovule is characterized by an extensive chalaza, vascularization and Anacardiaceae-type hypostase. The pachychalazal seed coat contains abundant vascular bundles and a tanniniferous hypostase. The inner epidermis of the inner integument differentiates into an endotegmen. The contribution of the integuments towards seed coat development is negligible. Concerning characters of the disc in the female flower, the meso- and endocarp, as well as seed size, degree of pachychalazy, nutrient reserves (starch) in the chlorophyllous cotyledons and hypogeal germination, Heeria shows a very close phylogenetic relationship to Protorhus longifolia. However, fruit and seed structure clearly supports the taxonomic separation of Heeria from Ozoroa. Data also support the view that Heeria is a tropical relict, and the hypothesis that pachychalazy, greater seed size, as well as recalcitrant seed viability behaviour constitute ancestral seed character states. Pachychalazy is regarded as a functional adaptation for more efficient transfer of nutrients.     

距药姜种子解剖学和组织化学研究

距药姜种子解剖学和组织化学研究表明,种子包括种皮、外胚乳、内胚乳和胚。外皮由1层表皮细胞构成,细胞壁纤维素质且明显增厚,中种皮可分为1层细胞的下皮层、半透明细胞层和2-4层细胞的色素细胞层,下皮层和色素细胞层的细胞内充满棕红色色素;内种皮由1层砖形薄壁细胞构成。珠孔区有珠孔领和孔盖的分化,但珠孔领分化不完善。合点区内种皮出现缺口,缺口间充满合点区色素细胞,其整体轮廓成新月形。外胚乳细胞壁平直,细胞内充满淀粉。内胚乳可分为多细胞区简细胞区两部分,内胚乳细胞界限不清,内含物主要是蛋白质,胚少有分化,含脂类、蛋白质、多糖,另外,还对姜花族的种子解剖学特征进行了初步的系统学分析。     

Pericarp formation in early divergent species of Arecaceae (Calamoideae,Mauritiinae) and its ecological and phylogenetic importance

Lepidocaryum tenue, Mauritia flexuosa and Mauritiella armata belong to the subtribe Mauritiinae, one early divergent lineage of the Arecaceae and one of the few of Calamoideae that occur in South America. These species occur in swampy environments and have fruits that are characteristically covered with scales. The objective of this study was to describe the formation of the layers of the pericarp within this subtribe and attempt to correlate fruit structure with the environment where species typically occur. Toward this goal, flowers in pre-anthesis and anthesis and fruits throughout development were analyzed using standard methods for light microscopy. The ontogeny of the layers of the pericarp of all three species was found to be similar. The scales were formed from non-vascularized emergences composed of exocarp and mesocarp. The median mesocarp accumulates lipids only in M. flexuosa and M. armata. The inner mesocarp together with the endocarp becomes papyraceous and tenuous in all species. This internal region of pericarp showed collapsed cells due to seed growth at the end of fruit development. Fruits of Mauritiinae are baccate, and the characters of the pericarp, especially the inner mesocarp and endocarp, help to maintain moisture. On the other hand, many species close to Mauritiinae show pericarp with sclerenchyma adjacent to the seed. This variation can contribute to understand the importance of this striking character in dispersal, germination and colonization in Arecaceae.     

A survey of ontogeny pericarp features as contribution to the infratribal characterization of Myrteae (Myrtaceae)

With the aim of correlating the pericarp structure with current phylogenies of Myrteae, this study describes the ontogeny in five species included in five out of the six South American clades of the tribe. In these taxa, the outer and inner ovarian epidermis gives rise to the exocarp and the endocarp, respectively, both with 1 layer. In the mesocarp, derived from the ovarian mesophyll, secretory cavities are arranged into a circle just below the exocarp and near the endocarp in Campomanesia adamantium; only below the exocarp in Eugenia pitanga and Myrcia multiflora; more internally in Myrciaria cuspidata, and below the exocarp and throughout the mesophyll in Myrceugenia alpigena. The promising traits for phylogenetic studies in the group include: direction of elongation of pericarp layers, regions that develop most in relation to the circle of larger vascular bundles, differentiation of spongy and sclerenchymatous tissues and position of secretory cavities.     

九翅豆蔻种子的解剖学和组织化学研究

九翅豆蔻种子包括假种皮、种皮、外胚乳、内胚乳和胚．由外珠被发育而来的种皮可划分为外种皮、中种皮和内种皮．外种皮由一层表皮细胞构成,其壁增厚并略木质化．中种皮包括下皮层、油细胞层和含２—５层细胞的色素层;各为一层薄壁细胞的下皮层与油细胞层非常压扁．内种皮由一层石细胞构成,极厚,占种皮厚度的１／３—２／３,是种皮主要的机械层;内种皮整体外观呈波浪形,在珠孔端和合点端的内种皮除外．种子在珠孔端分化出珠孔领和孔盖,在合点端分化出下皮细胞垫、大型薄壁细胞区、维管束和合点端色素细胞区．外胚乳细胞内充满淀粉,内胚乳细胞含有大量蛋白质和多糖,胚细胞含有蛋白质、多糖和脂类物质．脂类物质不存在于油细胞中,而存在于胚细胞、部分假种皮细胞、外种皮细胞和内胚乳最外层细胞中．建议将油细胞（层）改称为半透明细胞（层）．     

A water drop-shaped slingshot in plants: geometry and mechanics in the explosive seed dispersal of Orixa japonica (Rutaceae)

Background and AimsIn angiosperms, many species disperse their seeds autonomously by rapid movement of the pericarp. The fruits of these species often have long rod- or long plate-shaped pericarps, which are suitable for ejecting seeds during fruit dehiscence by bending or coiling. However, here we show that fruit with a completely different shape can also rely on pericarp movement to disperse seeds explosively, as in Orixa japonica.MethodsFruit morphology was observed by hard tissue sectioning, scanning electron microscopy and micro-computed tomography, and the seed dispersal process was analysed using a high-speed camera. Comparisons were made of the geometric characteristics of pericarps before and after fruit dehiscence, and the mechanical process of pericarp movement was simulated with the aid of the finite element model.Key ResultsDuring fruit dehydration, the water drop-shaped endocarp of O. japonica with sandwich structure produced two-way bending deformation and cracking, and its width increased more than three-fold before opening. Meanwhile the same shaped exocarp with uniform structure could only produce small passive deformation under relatively large external forces. The endocarp forced the exocarp to open by hygroscopic movement before seed launching, and the exocarp provided the acceleration for seed launching through a reaction force.ConclusionsTwo layers of water drop-shaped pericarp in O. japonica form a structure similar to a slingshot, which launches the seed at high speed during fruit dehiscence. The results suggest that plants with explosive seed dispersal appear to have a wide variety of fruit morphology, and through a combination of different external shapes and internal structures, they are able to move rapidly using many sophisticated mechanisms.     

砂仁种子的解剖学和组织化学研究

砂仁种子包括假种皮、种皮、外胚乳、内胚乳与胚。假种皮由内表皮、外表皮及其间的６－９层薄壁细胞组成。种皮分为外种皮、中种皮与内种皮。外种皮由１层表皮细胞构成,其壁增厚并略木质化。中种皮包括各含１层细胞的下层皮和半透明细胞层与含３－５层细胞的色素层;下皮层与色素层细胞均含有红综色素,后者的壁呈网状增厚。内种皮由１层内切向壁与径向壁非常增厚的石细胞构成。种皮表面具有许多疣状突起,它们是体积较小的表皮细胞     

象牙参种子的解剖学和组织化学研究

象牙参种子解剖学和组织化学的研究结果表明, 种子包括假种皮、种皮、外胚乳、内胚乳和胚。假种皮没有完全包被种子, 由约4~5 层薄壁细胞构成。种皮可以分为外种皮、中种皮和内种皮。外种皮由1 层表皮细胞构成, 细胞壁明显增厚;中种皮包括下皮层、半透明细胞层和3~4层细胞的色素层, 下皮层和色素层细胞均充满红棕色色素;内种皮由1 层体积小、壁局部增厚的砖形薄壁细胞构成。种子在珠孔端分化出珠孔领、孔盖和种阜状结构, 珠孔领为同形型, 孔盖不具石细胞硬层。合点区内种皮出现缺口, 缺口间充满合点区色素细胞, 其整体轮廓成新月形。外胚乳可分为厚区与薄区两部分, 外胚乳细胞壁平直, 细胞内充满淀粉。内胚乳细胞主要含蛋白质, 也有少量脂类物质, 细胞界限不清楚。胚棒状, 两端略膨大, 含大量脂类物质, 也含蛋白质和多糖。     

Pericarp anatomy of wild roses (Rosa L., Rosaceae)

The pericarp anatomy of representatives of all subgenera and sections of the genus Rosa was studied. All species have the same basic pericarp structure: it is composed of inner and outer endocarps, mesocarp and exocarp formed by the epidermis and hypodermis. The differences concern mainly the thickness of particular layers, and the shape and size of their cells. Cells of the endocarp and mesocarp are thick-walled. The only exception is Rosa rugosa mesocarp, which is composed of rather thin-walled cells with a large lumen. The endocarp structure of Rosa achenes resembles the drupe of the genus Prunus s.l. and drupelets of Rubus species.     

Comparative morphology and physiology of fruit and seed development in the two shrubs Rhus aromatica and R. glabra (Anacardiaceae)

Morphology and physiology of fruit and seed development were compared in Rhus aromatica and R. glabra (Anacardiaceae), both of which produce drupes with water-impermeable endocarps. Phenology of flowering/fruiting of the two species at the study site was separated by ∼2 mo. However, they were similar in the timetable and pattern of fruit and seed development; it took ∼2 mo and ∼1.5 mo for flowers of Rhus aromatica and R. glabra, respectively, to develop into mature drupes. The single sigmoidal growth curve for increase in fruit size and in dry mass of these two species differs from the double-sigmoidal one described for typical commercial drupes such as peach and plum. Order of attainment of maximum size was fruit and endocarp (same time), seed coat, and embryo. By the time fruits turned red, the embryo had reached full size and become germinable; moisture content of seed plus endocarp had decreased to ∼40%. The endocarp was the last fruit component to reach physiological maturity, which coincided with development of its impermeability and a seed plus endocarp moisture content of <10%. At this time, ∼50, 37, and 13% of the dry mass of the drupe was allocated to the exocarp plus mesocarp unit, endocarp, and seed, respectively. The time course of fruit and seed development in these two species is much faster than that reported for other Anacardiaceae, including Rhus lancea, Protorhus, and Pistacia.