Taxonomic significance of stem and leaf-sheath anatomy in Timmia Hedw.

Abstract

Sections of the stems and leaf sheaths of North American, European and Asiatic specimens of Timmia austriaca, T. megapolitana and T. norvegica were examined microscopically to discover useful discriminatory characters for identification purposes. The presence or absence of stereids in the sheathing part of the nerve appears to be a valuable taxonomic character for use in determining otherwise doubtful or unidentifiable sterile material of the sections Timmia (stereids present) and Timmiaurea (stereids absent). Similarly, the presence of a continuously thickened layer on the adaxial side of the sheathing lamina appears to be distinctive for T. norvegica. The characteristics of the stem seem to be of no taxonomic importance.     

Leaf anatomy inTigridieae (Iridaceae)

A biometric study of theSarcocapnos crassifolia complex from eastern Andalusia (Spain), Algeria, and Morocco was carried out. Twentytwo populations were used in a principal components analysis based on 14 variables. The results support the recognition of two species,S. crassifolia andS. pulcherrima, spec. nova. The taxon described byBoissier asS. speciosa (S. crassifolia subsp.Speciosa) is maintained inS. crassifolia.     

Taxonomic, evolutionary and ecological implications of the leaf anatomy of rhizomatous Iris species

The leaf anatomy of the rhizomatous Iris species with ensiform leaves and the related genera Pardanthopsis and Belamcanda is described. Their isobilateral leaves may or may not have a pseudo-dorsiventral structure. Variable characters of their leaf blades include: outline in transverse section, height and shape of papillae, form and structure of stomata, transverse section outline of marginal fibre strands and sclerenchy matous inner bundle sheath at phloem and xylem poles, forms of mesophyll arrangement, mesophyll structure and air canals, vascular bundle arrangement and the detailed structure of the larger vascular bundles, distribution of tannin, size and distribution of crystals. The taxonomic and ecological significance of these characters has been evaluated.
The anatomical characteristics of 25 supraspecific taxa in three genera are presented and compared in tables. The relationships and evolutionary position of these taxa are discussed. Each of the three subgroups within Iris appears to be correlated with a syndrome of anatomical characters. Some species currently of uncertain taxonomic position are discussed, and their classification based on anatomical data is suggested.
Some characters related to xeromorphy or helomorphy are mentioned.     

Taxonomic significance of leaf surface morphology in Aloe section Pictae (Xanthorrhoeaceae)

Leaf surface morphology was analysed in 32 species representing the maculate species complex (the poorly resolved section Pictae) in the genus Aloe (Xanthorrhoeaceae). Few comparative morphological data are available for the complex. Leaf surface and stomatal characters observed by scanning electron microscopy show taxonomically significant interspecific variation. Most species are characterized by irregularly outlined, four‐ to six‐sided epidermal cells, the periclinal walls of which are flat and embellished with micropapillae and the anticlinal walls of which are indicated by channels on the leaf surface. The outer stomatal pore is typically sunken or plane and surrounded by four lobes on the leaf surface that may overarch the epistomatal chamber. The guard cells have distinct outer and inner stomatal ledges. Two geographical groups, comprising southern and east African species, are distinguishable by their leaf surface morphology. These characters are diagnostic in A. ellenbeckii, A. prinslooi and A. suffulta and support changes in the delimitation of A. greatheadii, A. macrocarpa and A. swynnertonii. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 418–428.     

Taxonomic significance of leaf indumentum characteristics of the genusBiscutella (Cruciferae)

Leaf indumentum characteristics of 52 taxa of the genusBiscutella are examined by hand lens, stereo- and scanning electron microscopy. Hairs occur on all vegetative organs of all taxa exceptB. laevigata subsp.lucida which is completely glabrous and shining. Trichomes are simple unicellular and attenuate but are variable in structure, size and distribution both within and between species. Eight types of indumenta are recognized and these include hispid/hirsute, puberulent, tomentose, villous and velutious. Each type varies in abundance from sparse to dense within the genus. In a few cases, indumentum is species-specific; for example, the whitish tomentose hair covering ofB. frutescens distinguishes this species from the remaining species of the genus. In other taxonomically important species affinities are indicated. The occurrence of indumentum is discussed in relation to the various roles usually ascribed to this feature.     

Leaf anatomy and relationships of Dietes (Iridaceae)

The leaf anatomy of Dietes is described, including all 6 species. Characters support the morphological evidence that Dietes is a distinct genus and related to other Iridoideae. Certain features, notably the epidermal structure and sheath vasculature, distinguish it from other Iridaceous genera, although the sheath vasculature indicates a relationship with some New World Iridoideae. The leaf margin type is similar to that of other Old World Iridoideae. Many leaf anatomical characters in Dietes are associated with xeromorphy. Leaf anatomy supports the division of Dietes into 2 subgenera.     

Leaf anatomy and phylogeny of Ixioideae (Iridaceae)

Leaf anatomy is described in Ixioideae, the largest subfamily of Iridaceae, with particular reference to phylogeny and systematics. Leaves in many genera have two rows of opposing vascular bundles (found also in many other Iridaceae), sometimes (except in e.g. Pillansia) combined with typical ixioid features such as a prominent pseudomidrib, mesophyll cells often elongated at right angles to the leaf axis, and epidermal cells also sometimes slightly laterally elongated, frequently with markedly sinuous anticlinal walls, and a single row of papillae per cell. Other characters are limited to a few genera. Anatomical characters are used together with data from other sources to construct a cladogram for the group. Although anatomical characters in general show much homoplasy, the relationships of the existing three tribes, Pillansieae, Watsonieae and Ixieae, diagnosed mainly on the basis of floral and inflorescence characters, are largely upheld by analysis, with at least two potentially useful subtribal groupings within Ixieae.     

Leaf anatomy and systematics of Homeriinae (Iridaceae)

Leaf anatomy is described in a range of species of the Old World subtribe Homeriinae, including species from all of the eight genera: Barnardiella, Galaxia, Gynandriris, Hexaglottis, Homeria, Moraea, Rheome and Roggeveldia. Homeriinae have bifacial leaves, otherwise unusual among Iridaceae, and an apomorphy for this group. Leaf anatomy also shows some unusual features, notably an 'extra' row of (inverted) vascular bundles in some specieS. A cladistic analysis using a broad range of data demonstrates that Moraea, the largest genus of the subtribe, is paraphyletic. The smaller genera are consistently clustered within Moraea. Subgenus Moraea is heterogeneous and requires redefinition. Although there are insufficient existing data for satisfactory resolution of the relationships of Homeriinae, information from leaf anatomy provides some useful indicators.     

Taxonomic significance of leaf anatomy of Aniselytron (Poaceae) as an evidence to support its generic validity against Calamagrostis s. l.

A comparative study of leaf anatomy on Aniselytron Merr. and Calamagrostis Adans. s. l. was conducted to review the systematic status of Aniselytron Merr. Calamagrostis s. l. exhibits wide variation in many features, but basic leaf structures of the genus remain constant: absence of a midrib-keel; median and large vascular bundles are central, with double sheaths, accompanied by girders both adaxially and abaxially; prickles have a bulbous base and are not sunken; the abaxial epidermal cells are short and wide and relatively thick-walled. Aniselytron differs from Calamagrostis s. l. in: midrib-keel is present, consisting of a large central bundle with small ones on either side; all vascular bundles are abaxially situated, with abaxial girders only, parenchyma takes the place of the adaxial sclerenchyma; the bases of the prickles are sunken and are not bulbous; the abaxial epidermal cells are tall and thin-walled. These distinct anatomical features, in combination with the differences in spikelet structure and habitat, suggest that Aniselytron should be generically separated from and not merged with Calamagrostis s. l. Due to the adaxial parenchyma in the midrib which has never been found in Pooideae, Aniselytron might have a relationship with some other subfamily.     

Taxonomic significance of trichomes micromorphology in cucurbits

Studies on trichomes micromorphology using Scanning Electron Microscope (SEM) were undertaken in 23 species with one variety under 13 genera of the family Cucurbitaceae (viz., Benincasa hispida (Thunb.) Cogn., Citrullus lanatus (Thunb.) Matsum. & Nakai, Cucumis melo var. agrestis Naudin, Cucumis sativus L., Diplocyclos palmatus (L.) C. Jeffrey, Edgaria dargeelingensis C.B. Clarke, Gynostemma burmanicum King ex Chakr., Gynostemma pentaphyllum (Thunb.) Makino, Gynostemma pubescens (Gagnep.) C.Y. Wu, Hemsleya dipterygia Kuang & A.M. Lu, Lagenaria siceraria (Molina) Standl., Luffa acutangula (L.) Roxb., Luffa cylindrica M. Roem., Luffa echinata Roxb., Melothria heterophylla (Lour.) Cogn., Melothria leucocarpa (Blume) Cogn., Melothria maderspatana (L.) Cogn., Sechium edule (Jacq.) Sw., Thladiantha cordifolia (Blume) Cogn., Trichosanthes cucumerina L., T. cucumerina var. anguina (L.) Haines, Trichosanthes dioica Roxb., Trichosanthes lepiniana (Naudin) Cogn. and T. tricuspidata Lour.). The trichomes in the family Cucurbitaceae vary from unicellular to multicellular, conical to elongated, smooth to ridges, with or without flattened disk at base and cyctolithic appendages, thin to thick walled, curved at apices to blunt. Trichomes micromorphology in the family Cucurbitaceae was found significant taxonomically.     

Taxonomic significance of leaves in family Aizoaceae

Aizoaceae is one of the most important and widespread succulent plant families in both tropical/subtropical regions and arid zones. In this study, 27 species were collected from various floristic regions in Egypt, Kingdom of Saudi Arabia and cactus farms (Kalupia – Egypt). The morphological characteristics of every taxon were recorded. The important morphological features included: the number of leaves per plant; leaf types; leaf position (cauline or radical; the latter indicates leaves arising from, or near, the roots); leaf arrangement; petiolate or sessile leaves; leaf sheath present or absent; leaf shape; leaf margin; leaf tip; presence of leaf ‘window area’; leaf texture; and presence of white or dark miniscule dots (white miniscule dots from calcium carbonate and dark miniscule dots from tannin sacs). The investigated anatomical features were as follows: shape of the transverse section; the type of epidermal cells; the presence of large epidermal cells (bladder cells); presence of papilla and simple hairs; presence of tannin sacs; shapes of calcium oxalate crystals; shape of the xylem vessels; and the presence of Kranz unit (the unit that constitutes the vascular bundle/s, parenchyma sheath, and surrounding mesophyll) or collenchyma sheath. All data were recorded in a data matrix (as either text or numerical data), which was used to construct the identification key and phylogeny tree using a multi-variate statistical package. The results of our analysis may open the possibility of using the morphological and anatomical features of leaves to distinguish between the subfamilies, genera, and species of Aizoaceae.     

Taxonomic significance of the distribution of constituents of leaf cuticular waxes of Croton species (Euphorbiaceae)

Foliar epicuticular waxes of specimens of 13 Croton species native in Brazil were extracted. The fractions containing alkanes and primary alcohols were isolated by preparative thin layer chromatography. Derivatized n-primary alcohols were identified by gas chromatography (GC) coupled with mass spectrometry and n-alkanes by GC and comparison with known standards. Relative abundances were estimated by GC coupled with flame ionization detector. The distribution of constituents of both classes was analyzed by cluster analysis, using the UPGMA method and Euclidean distances. The chemical affinities among species were compared with published data of molecular phylogenetic relationships. The distribution of n-alkanes and primary alcohols were shown to be useful markers of Croton species. Primary alcohols were more consistent than n-alkanes for species fingerprinting.     

Taxonomic variation in total leaf protein amino acid compositions of grasses

Leaves of greenhouse grown grasses had free protein amino acid contents of generally less than 5 % total amino acids, while field collected grasses averaged 14.7 % free protein amino acid contents. Taxonomic patterns are detectable in the total leaf amino acid profiles of grasses from both sources, those of pooids being distinguishable from those of chloridoids and panicoids, and those of danthonioids showing an intermediate pattern. Leaf profiles of Oryza, Stipeae, and Ehrharteae resemble one another, and are more like those of pooids than those of panicoids. Variations in Thr and Leu are apparently associated with differences in photosynthetic pathway. Grass leaves are generally low in total amino acid contents (2.2 ? 1.0 g % fr. wt), with Ile, Val and Met + Cys identified as the limiting essential amino acids. However, the nutritional ‘chemical scores’ of grass leaf proteins are high (75 %, based on the WHO scoring pattern).     

Taxonomic significance of flavonoid variation in temperate species of Nothofagus

Forty-two flavonoids and a stilbene (pinosylvin) were identified in the leaf exudates of 11 temperate species of Nothofagus from South America, Australia and New Zealand. The flavonoid profiles demonstrate significant taxonomic value at the subgeneric level. Most species of subgenus Fuscospora are characterized by the presence of pinosylvin, galangin and galangin methyl ethers. Kaempferol-type flavonols are abundant in subgenus Lophozonia while these flavonols are largely absent from species of subgenus Fuscospora. The flavonoid patterns are largely in agreement with a recent subgeneric classification of Nothofagus.     

纯培养下拟茎点霉分生孢子的形成及意义

以18种共23个拟茎点霉菌株为材料,比较了在25℃、12h光照(40w日光灯)/d条件下不同培养基上甲、乙型分生孢子的形成情况。结果表明,苜蓿煎汁+Czapek培养基能促使多数拟茎点霉菌株形成甲、乙两型分生孢子,其形态及大小也与自然寄主上的相一致。根据纯培养获得的形态特征对原始描述缺乙型分生孢子特征记载的Phomopsis durionis, homopsis sterculicola, Phomopsis macadamii, Phomopsis lucumicola和Phomopsis tinea进行了补充描述。     

Taxonomic variation in total leaf protein amino acid compositions of monocotyledonous plants

Protein contents and protein amino acid compositions of different regions of leaf blades and of leaves representing different physiological ages, taken from Aranda Christine (Liliiflorae) and Languas galanga (Zingiberiflorae) showed little intraspecific variation. However, leaf amino acid compositions of 25 plant species covering the major taxonomic groups of the Monocotyledonae showed variation and group by group comparisons revealed taxonomic patterns.     

Taxonomic significance of floral pigments in linum (Linageae)

Floral pigments of 30 taxa, representing five informally ranked subgeneric complexes(Linum schiedeanum, L. virginianum,L. neomexicanum, L. sulcatum, andL. rigidum) of yellow-flowered North American flaxes, were examined by paper chromatography. Earlier studies, based on comparative gross morphology, chromosomal complements, and pollen structure, led to the conclusion that members of theL. schiedeanum complex may be the most primitive and that theL. virginianum, L. neomexicanum, andL. rigidum complexes may have been derived independently, the latter via a taxon similar toL. sulcatum. Data from both carotenoids and flavonoids support this scheme. Spectral analysis reveals the exclusive presence of the Β-carotenoid, violaxanthin, in the X.schiedeanum, L. virginianum, L. neomexicanum, andL. sulcatum com-Taxa of theL. rigidum complex, with the exception ofL. subteres, possesplexes. exclusively the α-carotenoids, lutein and its 5, 6-monoepoxide.L. subteres, in its production of violaxanthin, provides a chemical link to the other complexes, though possession of several species-specific flavonoids suggests an early divergence from other members of theL. rigidum complex. Distinctions in the Chromatographic patterns of quercetin, luteolin, and other flavonoid compounds were found among the five groups. In general the loss of flavonoid pigments may be correlated with increased morphological specialization. Identical patterns in certain species of theL. schiedeanum andL. virginianum complexes support the presumed relationship between these two groups.