Morphological and Anatomical Studies of Linaria Species from South-west Spain: Seeds

Seeds of 24 taxa of Linaria from south-west Spain were examinedwith a scanning electron microscope and light microscope. Basedon seed features such as shape, surface ornamentation and cellshape, seven morphological types were recognized. Seeds of thedifferent types are described, illustrated and compared. A keyto distinguish the different species or groups of species isprovided. Copyright 1999 Annals of Botany Company Seed-coat, SEM, anatomy, Scrophulariaceae, Antirrhineae, Linaria .     

SEED COAT MORPHOLOGY IN CORDYLANTHUS (SCROPHULARIACEAE) AND ITS TAXONOMIC SIGNIFICANCE

A study of seed coat sculpturing in Cordylanthus (Scrophulariaceae—Rhinantheae) using the scanning electron microscope (SEM) shows that seed surface patterns are characteristic and constant for a given species or a group of species. Seeds of 23 species were examined and classified into four types (irregularly crested, deeply reticulate, shallowly reticulate, and irregularly striate) based on differences in the reticulated seed coat. Anatomical studies of sections with the light microscope show that the reticular patterns result from enlargement of the epidermal cells of the integument, followed by formation of characteristic wall patterns through lignification. Seed characters furnish useful data for formulating the taxonomy of Cordylanthus both on the sectional and subsectional level and for the delimitation of certain species. Seed coat morphology offers evidence for including the genus Dicranostegia in Cordylanthus and for maintaining C. hispidus and C. palmatus as separate species. The distinctness of two seed coat types within section Cordylanthus suggests two major phylogenetic lines within this section.     

Seed Coat Microsculpturing in Brassica and Allied Genera (Subtribes Brassicinae, Raphaninae, Moricandiinae)

To obtain new information on the taxonomy of Brassica and alliedgenera, seed surfaces of 44 species (78 accessions) belongingto 11 genera of subtribes Brassicinae, Raphaninae and Moricandiinaewere examined using a scanning electron microscope. Ten typesof basic ornamentation patterns were recognized. While fourtypes were represented by only one species each, six types hadmore than one species either representing one genus (two types)or more (four types). The different species in each of the sixtypes could generally be distinguished from each other on thebasis of differences in microsculpturing features. This analysisprovides evidence for the close relationship among the variousgenera within the subtribe Brassicinae, and also the closenessof Raphanus, Enarthrocarpus and Moricandia of subtribe Raphaninaeand Moricandiinae, respectively, with the Brassicinae. Copyright2000 Annals of Botany Company Brassicinae, Moricandiinae, Raphaninae, SEM, seed coat microsculpturing, taxonomic implications     

Systematic implication of seed micromorphology in Arenaria (Caryophyllaceae) and allied genera

Variations in seed micromorphology of 64 taxa of Arenaria and allied genera were examined using scanning electron microscopy (SEM) in order to evaluate their diagnostic value for systematic studies in the genus and providing additional evidence on delimitation of natural groups. Significant diversity was found in seed coat morphology both among and within genera. Size, color, and shape of seeds appear to be of low importance at species level but provide useful evidence at generic rank. Cerastium and Stellaria are well distinguished from Arenaria by serrate seed margins and solid columellae on testa cells. The sculpturing pattern renders most characters potentially applicable in taxonomy and phylogeny assessment in Arenaria. The studied taxa show four basic types of sculpturing, viz. colliculate, rugose, papillate, and smooth. The colliculate type which is characteristic for the core group of Arenaria (A. subg. Arenaria) can be further divided into five subtypes. The smooth seed surface with indistinct cell boundaries represents a synapomorphy for A. subg. Leiosperma, whereas the winged seeds along with rugose surface characterize subg. Odontostemma. Otherwise seed micromorphology rarely provides adequate evidence for separation of natural groups, especially at sectional rank. We hypothesize that the seeds are highly polymorphic in certain groups of taxa showing recent adaptive radiation, such as the annual species of Arenaria, and do not provide strong support for natural groups within the genus.     

Morphology and distribution of antennal sense organs and diversity of mouthpart structures in Odontopus nigricornis (Stall) and Nezara viridula L. (Hemiptera)

Sensilla on the antennae and labial tip of the adult hemipteran bugs, Odontopus nigricornis Stall (Pyrrhocoridae) and Nezara viridula L. (Pentatomidae) (Hemiptera) were examined with an electron microscope in order to study their morphology, distribution, and possible chemo- and mechanoreceptive functions for food detection. The antenna contains 2 types of sensilla trichodea and 3 types of sensilla basiconica on the flagellar segments. S. trichodea are most abundant in both insects. Long slender hairs with elevated bases, and slightly shorter hairs with flexible sockets at the bases are common in both species. However, on each antennal segment of O.nigricornis, 1 or 2 rows of very long trichodeal hairs with longitudinal grooves and blunt tips are visible. At the periphery, S. basiconica with bulbous bases were also observed in addition to sensilla chaetica. The tripartite apex of the labium in both species consists of 2 lateral lobes and an apical plate. Each lateral lobe possesses a field of 11 thick-walled uniporous peg sensilla and long non-porous hair sensilla. Mandibular stylets of O.nigricornis have barbs, which may help in penetrating the hard seed coat. These insects made circular holes while feeding on the seed. A possible mechanism of feeding is discussed.     

Seed characteristics and testa textures of Pratensis, Orobon, Lathyrus, Orobastrum and Cicercula sections from Lathyrus (Fabaceae) in Turkey

The seed morphologies and testa textures of 23 taxa belonging to the Pratensis, Orobon, Lathyrus, Orobastrum and Cicercula sections of Lathyrus that can widely be found in Turkey were analysed. The findings obtained in this study and previous findings (34 taxa in total) were compared and interpreted at the level of the sections. Morphological properties including seed size, general shape, surface shape, colour, hilum length and width were measured under stereomicroscopy. The seeds were of spheroidal, subprolate and prolate (P/E = 0.90–1.58) types and medium in size. The smallest seeds belonged to Lathyrus inconspicuus var. inconspicuus (P = 2.19 ± 0.25 mm, E = 2.08 ± 0.16 mm) and the largest to L. sativus (P = 5.88 ± 0.74 mm, E = 5.36 ± 0.57 mm). The smallest hilum belonged to L. inconspicuus var. stenophyllus (0.38 ± 0.04 mm) and the largest to L. sylvestris (4.50 ± 0.58 mm). Testa textures such as papillae shape, dense, ribbing and presence or absence of a waxy layer were examined using scanning electron microscopy (SEM). In addition, some photographs included in this study were taken via stereomicroscopy and SEM.     

Scanning Electron Microscope Study of the Root-knot Nematode (Meloidogyne incognita) on Tomato Root

This study examines the types of structural information that can be gained by utilizing the scanning electron microscope (SEM) and a cryofracture technique to examine the host-parasite interaction. Roots of tomato, Lycopersicon esculentum cv. Marglobe, were cultured aseptically and inoculated with the root-knot nematode, Meloidogyne incognita. Twenty-four hours to four weeks after inoculation, developing galls were removed from the cultures and processed for SEM observation. The cryofracture technique was used to reveal internal structural features within the developing galls. The results illustrate structural details concerning penetration of the roots, differentiation of syncytia, and development of the nematodes beginning with the second-stage larvae and ending with adult egg-laying females.     

中国独行菜属种皮微形态特征的研究

利用扫描电子显微镜对独行菜属9种植物种子的种皮微形态进行了研究,结果表明独行菜属种皮微形态可划分为4种类型;结果支持将独行菜属划分为3个组的观点;北美独行菜在种皮纹饰上与其它类群差别较大,并结合子叶缘倚胚根的特征将其另立一新组——子叶缘倚组Sect. Accumbentum F. Z. Li, J. Q. Zheng ＆ Z. Y. Sun , sect. nov.     

Seed morphological diversity of Pedicularis (Orobanchaceae) and its taxonomic significance

Mature seeds of 109 species of Pedicularis representing 13 groups according to Tsoong’s infra-generic classification were investigated using light microscopy (LM) and scanning electron microscopy (SEM). The largest seeds occurred in P. superba (4.82 ± 0.32 mm × 2.18 ± 0.18 mm) and the smallest in P. crenata (0.95 ± 0.16 mm × 0.72 ± 0.08 mm). The individual seed weight ranged from 0.20 to 9.52 mg. There were two types of primary ornamentation, i.e. reticulate and undulate. Reticulate seeds were found in all examined species except for P. pantlingii and P. confluens. The reticulate seeds were divided into three subtypes, i.e. cristate-reticulate, regular-reticulate and membranous-reticulate. Among them, the cristate-reticulate and the undulate primary ornamentation are firstly reported. The inner tangential wall ornamentation was categorized into granulate, ruminate or striate. Seed characters seem to support the transfer of Pedicularis to Orobanchaceae from traditional Scrophulariaceae. Seed length, individual seed weight, primary ornamentation and inner tangential wall ornamentation were considered as potentially useful characters for infra-generic classification. Non-metric multidimensional scaling (NMDS) analyses indicated a clustering of some species in group 1 (Sceptrum) and all species in group 6 (Cyathophora), respectively. However, seed data were not highly congruent with Tsoong’s classification for delimitation of existing groups. Some characters, such as seed shape, primary ornamentation, inner tangential wall ornamentation and epidermal cell shape could be applied to identification of some species in this genus.     

珍珠菜属植物种皮微形态特征及其系统学意义

利用光学显微镜和扫描电镜对11种珍珠菜属植物种皮微形态特征进行了研究。根据种皮微形态特征,可以明显的划分为两种类型,即黑腺珍珠菜型和金爪儿型。珍珠菜亚属的7种植物均属于黑腺珍珠菜型,黄连花亚属的4种植物均属于金爪儿型。种皮微形态特征支持以雄蕊群的构造为主要依据的属下分类系统,在亚属级水平具有重要的分类学意义。     

Numerical analyses of seed morphology and its taxonomic significance in the tribe Nigelleae (Ranunculaceae)

We examined the seed morphology of Nigella, Garidella and Komaroffia to aid systematics and taxonomy. The seeds of 21 taxa in 20 species from Mediterranean and West Asian countries were studied using both zoom stereo and scanning electron microscopy (SEM). Principal coordinate analysis (PCoA) and unweighted average linkage analysis (UPGMA) were performed to assess the contribution of seed characters to the taxonomy of the tribe. Representative pictures from zoom stereo microscopy and SEM studies and measurement of seeds are presented. Most studied species showed unique seed surface sculpturing features, and seed shape, size and surface sculpturing separated the studied taxa into five main groups. However, the variation in seed shape and color were found to be in conflict with the generic taxonomy while macromorphological characters were found more congruent with the sectional taxonomy than with the generic taxonomy. Five main types of seed ornamentations – rugulose + striate, granulate, smooth, rugulose and mucronulate – were identified. Patterns in seed micromorphology strongly supported the sectional level taxonomy of Nigella. Two of the three sections of the genus were found to be well differentiated in terms of seed characters. Furthermore, seed morphology alone provide good support to Garidella as a distinct genus, but shows less taxonomic value for Komaroffia.     

Seed morphology and endosperm structure of selected species of Primulaceae, Myrsinaceae, and Theophrastaceae and their systematic importance

Seed size and shape, seed coat surface pattern, seed coat thickness, and endosperm structure were investigated in Androsace septentrionalis, Cortusa matthioli, Hottonia palustris, Primula elatior, Soldanella carpatica (Primulaceae), Anagallis arvensis, A. minima, Cyclamen purpurascens, Glaux maritima, Lysimachia nemorum, L. vulgaris, Trientalis europaea (Myrsinaceae), and Samolus valerandi (Theophrastaceae). Three seed size categories were distinguished on the basis of biometric measurements. Almost all seeds examined were found to be small with an angular shape classified as sectoroid or polyhedral. A new type of seed shape, suboval, was identified for H. palustris. Cyclamen purpurascens seeds differed from seeds of all other species examined because of their large size, subglobose shape, and concave hilar area. Despite the different shape types, the length/width ratio of the seeds examined was constant, while their hilum length/width ratio was a highly variable feature. Three types of seed surface patterns were observed: (1) reticulate, (2) tuberculate with secondary striations, and (3) poroid-alveolate with the presence of a spongy outer layer. For seeds of Anagallis arvensis, A. minima, Cortusa matthioli, Lysimachia nemorum, and Soldanella carpatica, secondary seed sculpture was described. The seed coats of all species examined were two-layered, and great differences in testa thickness were found (9.9?C128.6???m). In general, seeds of the Myrsinaceae species were more often characterized by thick testa. Different proportions in thickness of the inner and outer testa layers were observed. In seeds with reticulate seed patterns, the inner testa layer was twice to several times thicker than the outer layer, while the opposite proportions were observed in seeds with the tuberculate or poroid-alveolate seed sculpture pattern. In seeds of all species examined, oxalate crystals were present on the surface of the inner testa layer. Thus, the presence or absence of oxalate crystals in testa is not a feature distinguishing species with angular or subglobose seeds. Four types of endosperm structure were identified according to the thickness of the endosperm cell walls and the relief of their inner surface: (1) with evenly thickened and smooth cell walls, (2) with evenly thickened cell walls and circular or helical thickenings on their inside surfaces, (3) with very thick, but not evenly thickened cell walls with constrictions (??pitted??), and (4) with very thin papery and undulate cell walls. There is no rule concerning the seed shape, type of the seed sculpture, testa thickness, or endosperm structure that corresponds to the family affiliation of the species examined.     

Spontaneous and heat shock-induced irregularities in the cell structure of Didinium cf. nasutum

Deviations of the normal morphology and arrangement of the ciliary girdles and of the dorsal brushes of Didinium cf. nasutum are documented by SEM. Additionally, irregular fission stages such as symmetrical doublets which possess two parallel or antiparallel probosces are found in normal cultures. These ciliates are relatively long-lived (about one month). The didinia with oppositely oriented probosces feed continuosly on paramecia and produce normal cells which are indistinguishable from type-cells under a light microscope . Didinia with three or four probosces were not viable for longer than one to two weeks. All types of irregular forms could be induced experimentally by a 15-min exposure at 30 °C of cells cultured at 18 °C.     

Effects of bird seed dispersal on diversity of the invaded plants in several hedge types

The plants that invaded as weeds including woody weeds were surveyed in three hedge types, Euonymus japonicus(HEa), Viburnum awabuki (HV), and Deutzia scabra (HD), respectively, and two hedge types, Buxus microphylla var. sinica (HBa, HBb) cultivated in different habitats in Nanjing Botanical Garden Mem. Sun Yat-Sen (NBG), Nanjing of East China, from April 2001 to November 2002. Another hedge type, Euonymus japonicus (HEb) was also investigated as a contrast, cultivated in Nanjing Agricultural University (NAU), about 3 km away from NBG, between April and November 2003. In total, 1230 plant indi-viduals were found to have invaded these six hedge types, and were identified as belonging to 70 species in 57 genera and 42 fami-lies. Among these plants, 1047 individuals of 55 species were adapted for bird seed dispersal, and 161 individuals of 10 species were adapted for wind seed dispersal, but the seed dispersal mode of the other 22 individuals of five species was uncertain. Among the six hedge types, we found a significantly higher occurrence of bird-dispersed plant species than that of wind-dispersed species ( t = 5.086, df = 10, P < 0.0001) or that of species with the unknown dispersal mode ( t = 8.446, df = 10, P < 0.0001). However, the difference of occurrence between wind-dispersed species and species with the unknown dispersal mode was not significant ( t = 1.977, df = 10, P = 0.076). The number of bird-dispersed plant species recorded in the five hedge types of NBG varied from 15 to 36, M ± SD = 25.6 ± 8.1, and the Shannon-Wiener indices were between 2.151 and 2.917, M ± SD = 2.671 ± 0.306. In contrast with NBG, only 12 species of bird-dispersed plants occurred in the hedge of NAU, with a lower Shannon-Wiener index of 1.679. As a result of cluster analysis, based on Bray-Curtis similarity indices of the invaded plant species adapted for bird seed dispersal, the similarity of species composition of bird-dispersed plants between hedges was influenced to a large extent by the surrounding habitat characteristics, e.g., locality, seed source diversity, distances from seed sources, seed dispersing birds, and frequency of human disturbance, rather than simply being dependent on the hedge tree species themselves. This research suggests that hedges could attract birds to utilize their interior shelter as habitats, and therefore, would have enhanced the deposition of bird-dispersed seeds, as well as have favored seed-ling survival under hedges. Consequently, avian seed dispersal has enriched the species composition of each of the six hedge types consisting of just a single tree species. Although survival and colonization of the migrated plants will inevitably cause some influ-ences on the aesthetic view of hedges, these invaded weeds or woody weeds could be managed and suppressed through regular arti-ficial pruning and by eradication. The results indicate the ecological significance of seed sources, bird seed dispersal, and shrub patches in promoting the successional development of woody vegetation.     

Discopersicus n. gen., a New Member of the Family Tylenchidae ?rley, 1880 with Detailed SEM Study on Two Known Species of the Genus Discotylenchus Siddiqi, 1980 (Nematoda; Tylenchidae) from Iran

Discopersicus iranicus n. gen., n. comb., previously described from Iran as a new species under the genus Discotylenchus, is illustrated using light microscope and scanning electron microscope (SEM) observations and further studied using molecular characters. SEM studies revealed the newly proposed genus has oblique amphidial apertures on the lateral sides of the lip region. SEM images are also provided for two species of Discotylenchus, namely D. discretus and D. brevicaudatus, as the first SEM study of the genus. These results confirmed longitudinal amphidial aperture type on lateral sides of the lip region in genus Discotylenchus, as noted by Siddiqi while erecting the genus with D. discretus as the type species. Molecular phylogenetic analyses using partial small subunit (SSU) and large subunit (LSU) rDNA sequences revealed the affinity of the genus Discopersicus n. gen. with members of the subfamily Boleodorinae, as supported by morphological characters (mainly, the oblique amphidial opening).     

澳洲杨(大戟科)胚珠及其种子附属结构的个体发育研究

以澳洲杨的胚珠及其种子为材料,运用光学显微镜和电镜扫描的方法对其从胚珠发生直到种子成熟的个体发育过程和结构进行观察,同时与鸭脚西番莲的种子附属结构的发育过程进行对比研究。结果表明:(1)澳洲杨的珠孔类型为外珠孔类型,种子附属结构起源于珠孔而非珠柄,其为种阜,而非假种皮。(2)鸭脚西番莲的珠孔类型为内珠孔类型,种子附属结构起源于珠柄,并且最终将珠孔包被,其为真正的假种皮结构。通过种阜与假种皮的不同个体发育过程,建立了大戟科种阜与假种皮的不同发育模式,并对种子附属结构的生物学功能及其暗示的不同植物进化路径进行了讨论。     

Seed Size,Fecundity and Postfire Regeneration Strategy Are Interdependent in Hakea

Seed size is a key functional trait that affects plant fitness at the seedling stage and may vary greatly with species fruit size, growth form and fecundity. Using structural equation modelling (SEM) and correlated trait evolution analysis, we investigated the interaction network between seed size and fecundity, postfire regeneration strategy, fruit size, plant height and serotiny (on-plant seed storage) among 82 species of the woody shrub genus, Hakea, with a wide spectrum of seed sizes (2–500 mg). Seed size is negatively correlated with fecundity, while fire-killed species (nonsprouters) produce more seeds than resprouters though they are of similar size. Seed size is unrelated to plant height and level of serotiny while it scales allometrically with fruit size. A strong phylogenetic signal in seed size revealed phylogenetic constraints on seed size variation in Hakea. Our analyses suggest a causal relationship between seed size, fecundity and postfire regeneration strategy in Hakea. These results demonstrate that fruit size, fecundity and evolutionary history have had most control over seed size variation among Hakea species.     

Variation of seed heteromorphism in Chenopodium album and the effect of salinity stress on the descendants

Background and Aims

Chenopodium album is well-known as a serious weed and is a salt-tolerant species inhabiting semi-arid and light-saline environments in Xinjiang, China. It produces large amounts of heteromorphic (black and brown) seeds. The primary aims of the present study were to compare the germination characteristics of heteromorphic seeds, the diversity of plant growth and seed proliferation pattern of the resulting plants, and the correlation between NaCl stress and variation of seed heteromorphism.

Methods

The phenotypic characters of heteromorphic seeds, e.g. seed morphology, seed mass and total seed protein were determined. The effects of dry storage at room temperature on dormancy behaviour, the germination response of seeds to salinity stress, and the effect of salinity on growth and seed proliferation with plants derived from different seed types were investigated.

Key Results

Black and brown seeds differed in seed morphology, mass, total seed protein, dormancy behaviour and salinity tolerance. Brown seeds were large, non-dormant and more salt tolerant, and could germinate rapidly to a high percentage in a wider range of environments; black seeds were salt-sensitive, and a large proportion of seeds were dormant. These characteristics varied between two populations. There was little difference in growth characteristics and seed output of plants produced from the two seed morphs except when plants were subjected to high salinity stress. Plants that suffered higher salinity stress produced more brown (salt-tolerant) seeds.

Conclusions

The two seed morphs of C. album exhibited distinct diversity in germination characteristics. There was a significant difference in plant development and seed proliferation pattern from the two types of seeds only when the parent plants were treated with high salinity. In addition, seed heteromorphism of C. album varied between the two populations, and such variation may be attributed, at least in part, to the salinity.     

Purification and Characterization of Griffonia simplicifolia Leaf Lectins

Leaves from mature Griffonia simplicifolia plants were examined for the presence of leaf lectins possessing sugar binding specificities similar to the four known seed lectins (GS-I, GS-II, GS-III, GS-IV). Three (GS-I, -II, -IV) of the four known G. simplicifolia seed lectins were present in the leaves. Leaf G. simplicifolia lectins I and IV were similar to the respective seed lectins. Leaf GS-II, however, was composed of two types of subunits (M_r = 33,000 and 19,000), whereas the seed lectin consists of only one type of subunit (M_r 32,500). Seed and leaf GS-II lectins also had different isoelectric points. All leaf and seed lectins were similar with respect to their hemagglutination and glycoconjugate precipitation properties and all subunits contained covalently bound carbohydrate. Leaf GS-IV appeared slightly under-glycosylated compared to seed GS-IV.

The fate of GS-I and GS-II seed lectins in aging cotyledons was investigated. GS-I isolectins usually contain isolectin subtypes associated with each main isolectin. Upon inbibition and germination, these GS-I isolectin subtypes disappeared. Over time, GS-II lectin did not change its disc gel electrophoretic properties.

     

The systematic significance of seed morphology in Sagina (Caryophyllaceae) under scanning electron microscopy

The seed morphology of 15 species ofSagina from North America, Europe, and eastern Asia was studied, utilizing the scanning electron microscope, to determine the significance of seed coat features as taxonomic characters. There is variation in particular surface features within some members of the genus. However, superficial ridges and tubercules exhibit patterns very helpful in determining relationships among some species. Two basic seed types occur in the genus and are diagnostic at the sectional level. The saginoid seed, characteristic of sectionSagina, is obliquely triangular in outline, is grooved along the two dorsal ridges, and has slightly concave lateral surfaces. The crassuloid seed, characteristic of sectionMaxima, is obliquely reniform in outline, lacks dorsal grooves, and has shallowly convex lateral surfaces.