Breeding biology, resource partitioning and reproductive effort of a dioecious shrub, Clutia pulchella L. (Euphorbiaceae)

 The flowering of Clutia pulchella was studied in a coastal scarp forest community in southern KwaZulu-Natal, South Africa. Sex dependent differences in the frequency and magnitude of floral output were recorded, with male individuals producing 4.32 times more flowers per leaf axis than females. Increased node production, as a manifestation of significantly increased branching, allowed for prolific flower production in males. Energy investment per flower was marginally greater in females (0.045 J/mg), despite copious pollen production and glandular secretion in males (0.035 J/mg). Differential flower production, reproductive organ dry mass and an unbalanced branching ratio revealed that “per plant” expenditure towards flowering was more pronounced in males (♀ flowering × 5.04). The elevated cost of fruit production (♀ flowering × 5.5), inclusive of imperfect fruit set, resulted in overall reproductive expense being slightly higher for females. Such sex-dependent reproductive investment was shown to have minimal influence on the population sex ratio, with sex frequencies and nearest neighbor distances yielding a non-significant male bias of 1.16. No evidence of spatial asymmetry was found. Received December 1, 1999 Accepted September 27, 2000     

Hopenol-b,a triterpene alcohol from Euphorbia supina

In addition to the known triterpene motiol, hopenol-b (hop-22(29)-en-3β-ol) was isolated from the whole herb of Euphorbia supina. It has not been found previously in nature, though it has been prepared by both synthetic and biosynthetic methods.     

Methyl- and methylthio-phenanthrenes from Micrandropsis scleroxylon

The trunk wood of Micrandropsis scleroxylon W. Rodr. (Euphorbiaceae) contains besides sitosterol, stigmasterol and ferulic acid, three novel compou     

肥牛木根化学成分研究

从肥牛木(Cephalomappa sinensis)根的乙醇提取物中分离得到了7个化合物,经波谱分析确定其结构分别为:羽扇豆-20(29)-烯-2α,3β-二醇(1),苏门树脂醇酸(2),油桐酸(3),3-βstigmast-5-en-3-O--βD-xylopyranoside(4),东莨菪内酯(5),香草酸(6),油酸(7)。以上化合物均为首次从该植物中分离得到。     

Mite (Acari; Arachnida) diversity of two native plants in fragments of a semideciduous seasonal forest in Brazil

Studies to determine mite species richness in natural environments are still scarce, and have been conducted mainly in tropical ecosystems. The aim of this study was to determine the species richness of mites on two common native plants in fragments of the semideciduous seasonal forest in the Northwest of São Paulo State, Brazil. In each of eight fragments, 10 specimens of Actinostemon communis (Euphorbiaceae) and 10 of Trichilia casaretti (Meliaceae) were selected and marked. In total, 124 species of mites belonging to 21 families were found on the two plants. Tarsonemidae had the highest diversity (34 species), followed by Phytoseiidae (31), Tetranychidae (9) and Tenuipalpidae (8). Species accumulation curves for the two sampled plants did not reach an asymptote, even with the large sampling effort. Hence, it is estimated that a greater sampling effort may lead to an increase in species richness compared with what was found in this study. The richness of this mite fauna suggests that preservation of these plant species is important to maintain the mite diversity in these forest fragments.     

Pollen morphology of Trigonostemon and its relatives (Euphorbiaceae)

The pollen of Trigonostemon and the related genera Dimorphocalyx, Ostodes, Tritaxis and Jatropha (outgroup) has been studied with light microscopy, and scanning and transmission electron microscopy. The two major pollen types within Trigonostemon correlate well with macromorphological characters. Species belonging to the Trigonostemon reidioides type have pollen with ‘croton pattern’ ornamentation, a pistil with deeply divided stigmas (to at least half the length of the stigma arm) and stamens with a protruding appendage on the connective, while species of the Trigonostemon verrucosus type have verrucate (to almost gemmate) pollen, stigmas that are shortly cleft and stamens without an appendage on the connective. Dimorphocalyx, Ostodes, Tritaxis and Jatropha (outgroup) have similar pollen morphology, while Trigonostemon deviates from these genera in the absence of the ‘vertically’ striate ornamentation on the subunits. Therefore, when compared with an existing phylogeny of the Euphorbiaceae, the pollen characters of Trigonostemon appear to be derived. Moreover, because the ‘croton pattern’ ornamentation itself is widely shared by the ‘inaperturate crotonoids’, the loss of that structure in the Trigonostemon verrucosus type pollen is considered a further apomorphy.     

Microsatellite markers for the palaeotropic pioneer tree genus Macaranga (Euphorbiaceae) and their cross‐species transferability

We developed primer sequences for five polymorphic microsatellite loci in the tropical ant‐plant genus Macaranga (Euphorbiaceae). Population genetic parameters were determined on the basis of 30 individuals from each of two Macaranga species in Borneo. Allele numbers per locus ranged from three to 13. Expected and observed heterozygosities ranged from 0.160 to 0.850 and from 0.130 to 0.700, respectively. Four of the five primer pairs cross‐amplify polymorphic PCR products in a wide range of Macaranga species.     

Diterpenoids from Micrandropsis scleroxylon

The structure of micrandrol-C from Micrandropsis scleroxylon (Euphorbiaceae) is revised to 2,6-dihydroxy-7-methyl-1-methylthiophenanthrene. This and other micrandrols are probably diterpenes in view of their co-occurrence with micrandrol-D, the hemiketal of 1,2,3,4,9,10-hexahydro-6-hydroxy-4a-hydroxymethyl-1,1,7-trimethy-2-oxophenanthrene.     

Flavonol glycosides of Euphorbia retusa and E. sanctae-catharinae

The flavonoid glycosides of Euphorbia retusa and E. sanctae-catharinae are reported. Besides a number of common flavonol glycosides, kaempferol and quercetin 3-glucuronide-7-glucosides are reported for the first time.