Species Of Rhus Research Articles

A new species of Rhus (Anacardiaceae), endemic to serpentine near Barberton, Mpumalanga (Eastern Transvaal), South Africa

Rhus pygmaea , a new species endemic to amphibolitic serpentine soils near Barberton, Mpumalanga (Eastern Transvaal) is described and illustrated. It has affinities with R. pondoensis Schonlbut differs primarily in its dwarf habit, narrower leaflets, reduced inflorescence and male flowers having a conical pistillode.

Physiological dormancy and germination requirements of seeds of several North American Rhus species (Anacardiaceae)

AbstractFourteen seedlots of five species of Rhus were surveyed for presence/absence of physiological dormancy and/or for germination requirements of non-dormant seeds. Physiological dormancy was present in the four seedlots of R. aromatica studied, but not in either of the two seedlots of its close relative R. trilobata, which is in contrast to previous reports. Neither were seeds of R. glabra, R. typhina, nor R. virens physiologically dormant. Stratification at 5oC for 1 week or incubation in 500 or 1000 mg/l solutions of gibberellic acid broke physiological dormancy in > 90% of the R. aromaticaseeds. Maturation desiccation acted as a switch from a developmental to a germinative mode in R. aromatica embryos, whereas it was not required for germination of R. glabra or R. virens (R. trilobata and R. typhinanot tested). Seeds of all five species incubated on a moist substrate became fully imbibed in 2 d, at which time moisture content was approx. 70–80%of their initial weight. In general, germination of non-dormant seeds was rather insensitive to temperature and light. Seeds germinated equally well in light and in darkness over a daily (12 h/12 h) temperature range of 15/6–35/20oC. Over a 4 week period, the best germination percentages were obtained at 25/15 and 20/10oC, whereas 35/20oC appeared to be supraoptimal, though not always significantly so. If the incubation period was extended to 30 weeks, germination percentages were as high at 15/6oC as at 25/15 and 20/10oC.

The generic position of Lithraea brasiliensis Marchand (Anacardiaceae): evidence from fruit and seed structure

In Lithraea brasiliensis Marchand the exocarp is characterized by brachysclereids and the parenchymatous mesocarp by large secretory ducts; inner sclerenchymatous ridges are absent in die mesocarp. The stratified endocarp s. s. comprises a crystal layer, palisade-like brachysclereids, osteosclereids and macrosclereids. The osteosclereids are characterized by a distinct light line or linea lucida, which has hitherto also been recorded in a species of Rhus. In the partially pachychalazal seed, a typical Anacardiaceae-like hypostase typifies the chalazal part of the seed coat, while the integumentary seed coat reveals a well preserved outer epidermis, a compressed endotegmen and well developed inner cuticular layer. Our comparison of die characters of the ovule, fruit and seed of L. brasiliensis with those of various species of Rhus and other genera of the tribe Rhoeae (some closely related) presents evidence that L. brasiliensis could be most closely associated with the genus Rhus.

The generic position ofLithraea brasiliensisMarchand (Anacardiaceae): evidence from fruit and seed structure

InLithraea brasiliensisMarchand the exocarp is characterized by brachysclereids and the parenchymatous mesocarp by large secretory ducts; inner sclerenchymatous ridges are absent in the mesocarp. The stratified endocarps.s.comprises a crystal layer, palisade-like brachysclereids, osteosclereids and macrosclereids. The osteosclereids are characterized by a distinct light line orlinea lucida, which has hitherto also been recorded in a species ofRhus. In the partially pachychalazal seed, a typical Anacardiaceae-like hypostase typifies the chalazal part of the seed coat, while the integumentary seed coat reveals a well preserved outer epidermis, a compressed endotegmen and well developed inner cuticular layer. Our comparison of the characters of the ovule, fruit and seed ofL. brasiliensiswith those of various species ofRhusand other genera of the tribe Rhoeae (some closely related) presents evidence thatL. brasiliensiscould be most closely associated with the genusRhus.

Names of the southern African species of <i>Rhus</i> (Anacardiaceae) and their etymology

Brief notes on the origin of the scientific names of all the Rhus species recognized in the recent revision of the genus (Moffett 1993) are given, as well as a complete list of common names for each species. Recommendations are also made on those species which should he added to or removed from the National list of indigenous trees.

Comparisons of Allozyme Diversity Among Rare and Widespread Rhus Species

Genetic diversity in three species of Rhus was investigated using starch gel electro- phoresis. Rhus michauxii is a rare species endemic to North Carolina, whereas R. glabra and R. copallina are widespread. All three species are clonal, typically dioecious, woody shrubs. Forty-seven percent of the loci examined for R. michauxii were polymorphic, compared to 88% of the loci examined for both R. glabra and R. copallina. Mean genetic diversity (He) within populations of R. michauxii (0.05) was lower than the genetic diversity within populations of R. glabra and R. copallina (0.15 for both species). Mean number of multilocus genotypes per population was lower for R. michauxii, 4.1, versus the other two species, R. glabra, 27.5 and R. copallina, 26.6. Genotypic diversity indices (DG) were 0.41, 0.95 and 0.95 for R. michauxii, R. glabra and R. copallina, respectively. The proportion of genetic diversity among populations (GST) was higher in R. michauxii (0.335) and R. copallina (0.301) than in R. glabra (0.198). Genetic identity values among the species ranged from 0.52-0.96, and grouped R. michauxii closely with R. glabra. Rhus glabra and R. copallina have levels of genetic diversity similar to wide ranging plant species with the same suite of life history characteristics. The lower level of genetic diversity in R. michauxii is characteristic of species with limited geographic distributions. The relatively high levels of genetic diversity seen among populations indicates that clonal repro- duction may play an important role in the genetic structuring of these species.

Photosynthetic Responses of Heliophilous Rhus Species to Environmental Modification by Invasive Shrubs

This study aimed to determine the effect of overtopping and shading by the alien invasive plant species Acacia cyclops on the gas exchange characteristics and photosynthetic capacity of Rhus glauca and R. lucida, both indigenous heliophilous shrub species in the western Cape Province of South Africa. Overtopped individuals of both indigenous species showed morphological and physiological changes generally consistent with widely reported shade effects. However, R. lucida showed an apparently rare combination of unchanged maximum photosynthetic rate and increased apparent quantum yield under shaded conditions (...)

Typification of six Philip Miller names of temperate North American Toxicodendron (Anacardiaceae) with proposals (999–1000) to reject T. crenatum and T. volubile

SummaryReveal, J. L.: Typification of six Philip Miller names of temperate North American Toxicodendron (Anacardiaceae) with proposals (999–1000) to reject T. crenatum and T. volubile. ‐ Taxon 40: 333–335. 1991. ‐ ISSN 0040‐0262.When Philip Miller proposed Toxicodendron (Anacardiaceae) for those species of Rhus generally called “poison‐ivy” he accounted for six species from temperate eastern North America; previously, Linnaeus had recognized only two in Rhus. To date the Miller names have been essentially ignored, and none effectively typified. As now typified, T. pubescens becomes the earliest available name for the illegitimate T. toxicarium Gillis and for T. quercifolium (Michaux) E. Greene. Two Miller names are proposed for rejection, T. crenatum and T. volubile, to allow continued use of T. rydbergii Small ex Rydb. This is proposed simply to preserve nomenclatural stability.

Taxonomic position of Rhus problematodes (Anacardiaceae): Evidence from fruit and seed structure

This is the first report on the structure of the pericarp and seed coat of Rhus problematodes Merxm. & Roessl., a curious microphyllous shrublet of very limited distribution in the southern desert region of Namibia. Mainly on the basis of macromorphology, it was hitherto considered to stand somewhat apart from other African members of Rhus L. (sect. Gerontogeae Engl.). R. problematodes clearly agrees with other species of Rhus in its basic pericarp and seed-coat characteristics, including a single-seeded unilocular drupaceous fruit, parenchymatous mesocarp with secretory ducts, ridged outer endocarp, inner endocarp composed of three discrete layers, and an endotegmic, partially pachychalazal seed coat. The scarcity of stomata and heavy deposition of cutin in the exocarp possibly reflect adaptations to its arid habitat. Evidence from fruit and seed structure, combined with that from other sources, reconfirms the view that it is a highly specialized species of Rhus showing several xeromorphic, mainly macromorphological, reductions. The shared presence of glandular stellate hairs and reduced foliage leaves suggests that it might be closely allied to R. horrida Eckl. & Zeyh., a species from Namaqualand.

Relationships of herbivore feeding and plant flavonoids (Coleoptera: Chrysomelidae and Anacardiaceae: Rhus).

Eighteen leaf flavonoid compounds were isolated from several populations of Rhus tripartita from xeric habitats in Israel, ornamental Schinus terebinthifolius from Israel, and three species of Rhus (vulgaris, natalensis, tenuinervis) from mesic habitats in Kenya. Foodplant preference testing of Rhus-feeding Leaf Beetles (Blepharida sacra from Israel and B. marginalis and B. conradsi from Kenya) correlated well with the flavonoid composition of the different foodplants. Blepharida sacra and B. marginalis foodplant preferences demonstrated an herbivore sibling relationship but there is evidence, including foodplant ecology and distribution, that they are separate species. The herbivorefoodplant coevolution of the xeric B. sacra-R. tripartita is distinct from that of the mesic B. marginalis-R. vulgaris/natalensis, however, this study also indicates possible ancestral relationships between the herbivore species as well as between the plant species.

Polyphenols of some species ofRhus

Polyphenols of some species ofRhus

Reevaluation of the Sections of Rhus L. Subgenus Lobadium (Raf.) T. & G. (Anacardiaceae)

Species ofRhus subgen.Lobadium have in the past been grouped into five sections:Pseudosumac, Stypkonia,Pseudoschmaltzia, Rhoeidium andLobadium. Reexamination of the morphological criteria used to delimit the sections, as well as consideration of data from flavonoid chemistry and wood anatomy, suggest that the affinities of this group of taxa are best reflected by recognizing three sections and three subsections. The namesPseudosumac andPseudoschmaltzia are rejected as beingnomina nuda.

Introgressive Hybridization in Two Southern California Species of Rhus (Anacardiaceae)

Five populations ofRhus integrifolia andR. ovata were studied and, based upon morphological characteristics and pollen viability, a number of putative hybrids were found in those areas where the two species are sympatric. Diagnostic characteristics most useful for distinguishing the species and their hybrids are leaf morphology, sepal pubescence, petiole length, and petal size. Introgression was evident in at least three populations, which suggested that hybridization between the two species is an ancient phenomenon. Evolutionarily, hybridization between the two taxa has probably been of little consequence.

Rhus toxicodendron: possibility of systemic toxic effects.

IN RECENT years the question has been asked: Is it possible that systemic injury such as glomerulonephritis, the nephrotic syndrome, 1 periarteritis nodosa, 2 toxic encephalitis, 3 and even death * could be sequels of poison ivy dermatitis or of the administration of an extract of this plant. It is, therefore, expedient that we review the evidence for and against these possibilities or suspicions. It is an accepted fact that drugs may cause the nephrotic syndrome. The newer antiepileptic medications, trimethadione 6 and paramethadione 7 must be added to the list of drugs causing the nephrotic syndrome. In the American literature since 1770, there are only a few reports of systemic poisoning by the Rhus species of plants. For instance, Mr. Wilkes, 8 a student of medicine from Tennessee who was curious to test the truth of the statements made by some writers on the materia medica—that Rhus toxicodendron produces

The South African Species of Rhus L.

No abstract available

ハゼノキの葉の解剖殊にその樹脂道の分布に就て

Rhus succedanea grows in the warm districts in Japan, and is found in large quantities especially in Kyushu. I have studied the anatomical structure of the leaves of this plant, and especially the distribution of the resin canal. In the leaves of this tree, in each fibro-vascular bundle which has ordinarily a large resin canal in the phloem and which stands as a rule at the inner side of the group of bastfibre, but the developed fibro-vascular bundle has moreover smaller resin canals close by the cambium. These resin canals run parallel to the fibro-vascular bundles in any part, and those fibro-vascular bundles in the lateral veins branch off from those in the common petiole, and those in the veinlet from those of the lateral vein. A great many resin canals are found in the phloem of the common petiole, but in the lateral vein and veinlet there is only one resin canal. In an adult leaf, resin canals are found in the pith of the pulvinus and are also found in the bigger part of the veins too, but especially there are many resin canals in the pulvinus of the common petiole. In this part the resin canals are found at the periphery and inner part of the pith. Those at the inner part are very few, but at the periphery there are comparatively numerous resin canals, and the cross section sometimes much larger than that of the resin canals in the phloem. The resin canals in the phloem of the common petiole are most numerous at the middle·part of the first internode, and by and by the number diminishes as the internode becomes smaller. The petiole of the leaflets has four relatively large resin canals and any number of smaller ones, but there is only one at the end of the end of the midrib of the leaflets. In the petiole of the cotyledon, there are only two resin canals, but four in the petiole of the leaflets of the first common leaves of seedlings. All these resin canals enter into the midrib, but their number diminishes gradually, untill only one of them remains at the end of the midrib. While other species of Rhus have a great number of the trichome on their leaves, we can find only a very few of this species, and then only on the cotyledon, : the midrib of the common leaves of seedlings and on the scally leaves of the winter buds of the adult plant.

Fats from Rhus laurina and Rhus diversiloba

1. Substances more similar to Japan wax than to any other fat have been isolated from the ripe fruit of R. laurina and R. diversiloba. 2. A decrease in the poisonous properties of the fruit of R. diversiloba occurs simultaneously with the increase in fat content. 3. The decrease in the poisonous properties in the ripening of the fruit of R. diversiloba eventually results in the fruit becoming non-toxic. This phenomenon is not necessarily due to a chemical transformation of the poison into fat for: (a) subsequent to the formation of fat the cells in which it is deposited become filled with starch; (b) it is possible for the plant to transform starch into fat; (c) fat is not formed in the parenchymatous sheaths of the resin passages; (d) consequent upon the formation of fat, the resin passages are everywhere constricted by the growth of parenchyma sheaths; (e) a similar fat has been found in the fruit of a nonpoisonous species of Rhus.

On the Names of two Species of Rhus

On the Names of two Species of Rhus