New pair-spined species of Euphorbia (Euphorbiaceae) from Somalia

Eighteen new species of Euphorbia subgenus Euphorbia are described and their relationships discussed. All are endemic to Somalia, with limited distributions in the northern Regions. One, E. phillipsioides , has been identified mistakenly for some time as E. phillipsiae , which is shown to be conspecific with E. golisana. E. xylacantha , considered by N. E. Brown to be synonymous with E. monacantha , is reinstated as a distinct but variable species.     

Two new species of Euphorbia subsp. Euphorbia (Euphorbiaceae) from east and northeast Somalia

Two small species of succulent, spiny Euphorbia are described as new, both with limited distributions, E. ammophila from the coastal plain of eastern Somalia, and E. densispina from the mountain ranges of the northeast.     

Two new species of Monadenium (Euphorbiaceae) from Somalia

Two species of Monadenium, M. gillettii related to M. ellenbeckii , and M. lindenii related to M. virgatum are described as new endemics of Somalia.     

Two new species of Jatropha (Euphorbiaceae) from Somalia

The new species Jatropha miskatensis , from limestone slopes of the Cal Miskaat Range in north-eastern Somalia, and J. marmorata , from bushland on shallow soil over limestone just south of the Nugaal valley in north-eastern Somalia, are described. An illustration is provided for J. miskatensis.     

A new species of Phyllanthus (Euphorbiaceae) from Somalia

Phyllanthus lunifolius sp. nov., a completely prostrate dwarf shrub from limestone rocks in the coastal part of central Somalia, is described and illustrated.     

Andrachne fragilis (Euphorbiaceae), a new species from Somalia

Andrachne fragilis is described from north-facing limestone rocks of the escarpment in NE Somalia.     

New species of Maerua and Cleome (Capparaceae) from Somalia

The new species Maerua purpurascens (southern Somalia, on stabilized dune near coast) and Cleome kersiana (northern Somalia, on semi-desert gravel plain) are described and illustrated.     

Explosive seed dispersal in two perennial Mediterranean Euphorbia species (Euphorbiaceae)

The distance of explosive dispersal, its pattern in time, and the relative importance of autochory have been studied in two diplochorous species: Euphorbia boetica and E. nicaeensis. The seeds of E. boetica released by explosive dispersal reached a median distance of 156 cm and a maximum of almost 8 m, while the distances reached by the seeds of E. nicaeensis were lower: a median of 132 cm and a maximum of 5 m. The differences in explosive dispersal distance between species seem to depend on both seed mass and caruncle retention. The seeds of both species present a caruncle, but in E. boetica this is tiny, and in most cases is shed during the explosion of the capsules. The distances reached by the seeds of these species, dispersed just by capsule explosion, were similar to or greater than the distances to which ants disperse seeds in the Mediterranean sclerophyllous vegetation. Diplochorous plants may maximize either the distance of primary dispersal or that of secondary dispersal. Given that the seeds of E. boetica, that lose their caruncles, are not gathered by myrmecochorous ants, the results suggest that E. boetica maximizes its primary dispersal distance, whereas E. nicaeensis favors its secondary dispersal.     

Functional andromonoecy in Euphorbia (Euphorbiaceae)

The occurrence of cyathia containing staminate flowers but lacking a pistillate flower was studied in 17 species of Euphorbia. Male cyathia were found in the majority of species studied (88.2%) giving functional andromonoecy. In the male cyathia, the pistillate flower is generally totally absent, but sometimes a vestigial pistillate flower with a non-functional ovary is present. The proportion of male cyathia varied at both the population and species level. The position of male cyathia within the inflorescence showed a constant pattern among species: the proportion of male cyathia decreased from the first to the last levels of the pleiochasia. In general, perennial species had significantly higher proportions of male cyathia than annual species (mean 20 and 2.3%, respectively). In annual species there was a trend for production of male cyathia only in the first level of the inflorescence, whereas in perennials production up to the fourth level of the inflorescence was usual. Functional andromonoecy is common in Euphorbia and represents a new sex segregation in the genus. The selective forces causing this secondary sex segregation in Euphorbia, such as improved pollination or increased outcrossing, are discussed.     

Isolation and partial characterization of latex lectins from three species of the genus Euphorbia (Euphorbiaceae)

Three N-acetylgalactosamine-specific lectins were isolated from the latices of Euphorbia calcina L., Euphorbia dalberi L. and Euphorbia sp. (an undetermined species) by affinity chromatography on fetuin-agarose. They are all glycoproteins [about 12.5% (w/w) carbohydrate] of M, around 140 000 and appear to be tetrameric molecules composed of different subunits. All three lectins have similar amino acid (with high contents of asparagine/aspartic acid, giycine and leucine) and carbohydrate (with glucosamine, mannose.) fucose and xylose) compositions. In addition. they are closely related serologically.     

A New euglossine-pollinated species of Dalechampia (Euphorbiaceae) from Mexico

Dalechampia magnistipulata is described from Veracruz, Mexico. Belonging to sect.Scandentes, it has passed asD. tiliifolia Lam., but is not closely related to that or to any other Meso-american species. Its nearest affinity may be with South American species such asD. stipulacea andD. variifolia.     

New endemic species of Aneilema and Commelina (Commelinaceae) from Somalia

Three new, endemic species of Commelinaceae from central and southern Somalia are described. Aneilema trispermum is unique in the genus in having capsules with three one-seeded locules. The annual, buff-orange-flowered Commelina arenicola differs from the annual C. subulata Roth and related perennials in having a capsule with an indehiscent dorsal locule. Commelina frutescens has a unique shrubby habit.     

Photosynthetic nitrogen-use efficiency in leaves of woody and herbaceous species

1. Photosynthetic characteristics of an annual herb, Chenopodium album , and an evergreen tree, Quercus myrsinaefolia , were compared to clarify causes of the difference in photosynthetic nitrogen-use efficiency (photosynthetic capacity per unit nitrogen) between leaves of herbaceous and evergreen species.
2. When leaves with the same nitrogen content on an area basis were compared, photosynthetic capacity of C. album was twice as high as that of Q. myrsinaefolia . Gas-exchange measurements showed higher intercellular CO₂ concentration in C. album . Biochemical analyses indicated larger allocation of nitrogen into ribulose-1,5-bisphosphate carboxylase, a key enzyme of photosynthesis, and higher specific activity of ribulose-1,5-bisphosphate carboxylase in C. album . However, these differences were not large.
3. Compositional deviation of ¹³C in leaves of the two species suggested that the drop of CO₂ level between the intercellular space and the chloroplast was slightly larger in Q. myrsinaefolia when compared between the leaves with the same photosynthetic capacity.
4. It is concluded that the difference in photosynthetic nitrogen-use efficiency between C. album and Q. myrsinaefolia is not caused by a sole factor that is markedly different between the two species but by several factors each of which is slightly disadvantageous to Q. myrsinaefolia compared with C. album .     

Plant fecundity and pre-dispersal reproductive losses in a common and a rare Euphorbia species (Euphorbiaceae)

Comparative studies on the reproductive biology of closely related plant species have provided valuable information to understand the causes and consequences of common-rare differences with possible applications for the management of threatened populations. The magnitude and spatiotemporal variability of seed production and pre-dispersal reproductive losses were studied for 3 years in the rare endemic Euphorbia welwitschii and in its widespread congener E. characias. The factors responsible for a decrease in potential seed production in these species were the lack of a functional ovary in the cyathium, ovary and fruit abortion, seed predation by insects and seed abortion. In E. characias, the moth Acroclita subsequana was also responsible for minor reproductive losses. The proportion of male cyathia varied significantly between seasons, populations and species, being consistently higher in E. characias than in E. welwitschii. Reproductive losses that resulted in ovary, fruit and seed abortion affected mostly the endemic species and were heavier in the populations located near the sea due to local adverse climatic conditions. Seed predators inflicted higher reproductive losses to the endemic species than to its widespread congener and their impact was particularly heavy at Risco. The two Euphorbia species differed markedly in cyathia production, with E. welwitschii producing systematically a lower number of cyathia than its widespread congener and this, together with higher levels of ovary, fruit and seed abortion, seemed to be the main reasons for the low reproductive output of this rare species.     

A new species of Otostegia (Lamiaceae) from Somalia

A new species from gypsum plains in northern Somalia, Otostegia ericoidea Ryding is described and illustrated.     

Two new species of Polygala (Polygalaceae) from Somalia

The new species Polygala praetermissa , a dwarf perennial herb growing in stony places on limestone, and P. dasanensis , a shrublet apparently confined to gypsum, are described. Both species occur in the Cal Miskaat Range in north-eastern Somalia, but P. praetermissa has a wider distribution in northern Somalia.     

Two new species of Acalypha (Euphorbiaceae) from Peru

Two new species of the genus Acalypha are described and illustrated., A. salicina and A. simplicistyla , based on Peruvian material. Comments on the systematics of related species are included.     

A new species of Polycarpaea (Caryophyllaceae) from Somalia

The new species Polycarpaea basaltica , from an area of basalt rocks at the coast of northern Somalia, is described and illustrated.     

Two new species of Vigna (Leguminosae) from Somalia

The new species Vigna monantha ( V. subgen. Vigna sect. Catjang ) from coastal dunes of northern and central Somalia, and V. virescens ( V. subgen. Macrorhynchus ) from the inland of central and southern Somalia are described and illustrated. V. virescens is unique in Vigna by having branched stylar hairs, a character indicating a relationship between V. subgen. Macrorhynchus and the monotypic Wajira.     

Two new species of Acalypha (Euphorbiaceae) from Bolivia

Two new species of Acalypha, A. neeana and A. machiensis, are described and illustrated based on Bolivian specimens. Comments on the systematics of related species are included.