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.     

Euphorbia venkatarajui sp. nov. (Euphorbiaceae) from Eastern Ghats of Andhra Pradesh,India

Euphorbia venkatarajui, a new succulent species of Euphorbiaceae, is described from Kurnool district of Andhra Pradesh state, India. The new species belongs to the subgenus Euphorbia, and it closely resembles Euphorbia gokakensis S.R. Yadav, Malpure and Chandore and E. caducifolia Haines., but differs in certain distinct characters.     

A new spiny Euphorbia (Euphorbiaceae) species from northeast Somalia

A small succulent, spiny Euphorbia is described as a new species, E. patentispina , endemic to Somalia, with a limited distribution in the northeast region of Bari. Its relationship to other species of the same group—those producing subsessile capsules and a single spine from each spine shield—occurring in northern Somalia is discussed.     

Drought-tolerant succulent plants as an alternative crop under future global warming scenarios in sub-Saharan Africa

Globally, we are facing an emerging climate crisis, with impacts to be notably felt in semiarid regions across the world. Cultivation of drought-adapted succulent plants has been suggested as a nature-based solution that could: (i) reduce land degradation, (ii) increase agricultural diversification and provide both economic and environmentally sustainable income through derived bioproducts and bioenergy, (iii) help mitigate atmospheric CO₂ emissions and (iv) increase soil sequestration of CO₂. Identifying where succulents can grow and thrive is an important prerequisite for the advent of a sustainable alternative ‘bioeconomy’. Here, we first explore the viability of succulent cultivation in Africa under future climate projections to 2100 using species distribution modelling to identify climatic parameters of greatest importance and regions of environmental suitability. Minimum temperatures and temperature variability are shown to be key controls in defining the theoretical distribution of three succulent species explored, and under both current and future SSP5 8.5 projections, the conditions required for the growth of at least one of the species are met in most parts of sub-Saharan Africa. These results are supplemented with an analysis of potentially available land for alternative succulent crop cultivation. In total, up to 1.5 billion ha could be considered ecophysiologically suitable and available for succulent cultivation due to projected declines in rangeland biomass and yields of traditional crops. These findings may serve to highlight new opportunities for farmers, governments and key stakeholders in the agriculture and energy sectors to invest in sustainable bioeconomic alternatives that deliver on environmental, social and economic goals.     

Euphorbia gokakensis sp. nov. (Euphorbiaceae) from sandstone formations in Karnataka,India

Euphorbia gokakensis, a new succulent species of Euphorbiaceae, is described from the Belgaum district of Karnataka, India. The new species belongs to Euphorbia subgen. Euphorbia, and closely resembles Euphorbia caducifolia Haines. However, it is distinguished by its characteristic dwarf habit forming a compact cushion that hardly exceeds 50 cm in height.     

Fire survival of the Critically Endangered succulent,Euphorbia clivicola R.A. Dyer – fire-avoider or fire-tolerant?

The hypothesized ultimate agent of decline for one of the only two known populations of Euphorbia clivicola R. A. Dyer, a Critically Endangered species endemic to the Northern Province of South Africa, is the unsuitable fire management practised within the Nature Reserve in which the population is protected. Management recommendations concerning the fire regime need to consider fire survival in this succulent species. Fire survival of succulents may be due to the avoidance of fire in refugia or due to fire tolerance by vegetative recovery. Subsequent to a fire, damage to E. clivicola plants was determined. New growth (post-fire resprouting) and rock cover surrounding plants were assessed to determine whether plants tolerated fire through vegetative regrowth or survived fire through protection in refugia. Plants were found to be tolerant of fire, sustaining only mild damage with apparent fire mortality at 3% (2% of the plants were already dead prior to the fire). Fire damage stimulated vegetative regrowth, regrowth being more common in plants that had sustained higher levels of fire damage.     

Continued decline in tree euphorbias (Euphorbia tetragona and E. triangularis) on the Great Fish River Reserve,Eastern Cape,South Africa

A dramatic decline averaging 43% over a 4‐year period has occurred in tree Euphorbia (Euphorbia tetragona and Euphorbia triangularis) populations on the Great Fish River Reserve, South Africa. These changes are evident from data gathered by general vegetation monitoring methods as well as from a focused study of four tree Euphorbia populations. The decline from 2003 to 2007 was more marked for E. triangularis than for E. tetragona and was accompanied by a general absence of seedlings and a reduced presence of younger age classes of both species, decreasing the proportion of younger trees in the populations. The role of megaherbivores, specifically the black rhinoceros, in these changes is well established. However, the impact of baboon activity, leading to damage to tree crowns and upper branches, is also substantial, especially on E. triangularis populations. Damaged crowns were recorded significantly more often for E. triangularis than for E. tetragona, and the damage frequency increased with decreasing tree height. Thus, our work provides the first evidence that these two closely related Euphorbia species may be affected differently by herbivory.     

Laticifer starch grain morphology and laticifer evolution in Euphorbia (Euphorbiaceae)

The micromorphology of starch grains in the nonarticulated laticifer was examined in 200 taxa of succulent and nonsucculent Euphorbia. Rod, spindle, osteoid, discoid and intermediate shapes were found in latex. These unusual starch grain shapes are assumed derivatives from more rounded grains present in other angiospermous cells. Unbranched, rod–shaped grains were present in latex of annual and perennial herbaceous taxa. Spindle, osteoid, and discoid shapes, often branched, occurred in xerophytic, succulent taxa. Leafy taxa in several subgenera possessed rod–shaped grains. Taxa of the primitive subgenus, Esula , possessed the shortest rod–shaped grains derived from rounded grains common in parenchyma. Length of rod–shaped grains increased through herbaceous subgenera and culminated in Poinsettia where grain length may be extremely great. Dwarf or shrubby succulents with thickened roots have osteoid grains. Shrubby or arborescent coralline and cactiform species, specialized taxa, possessed large branched grains. Grain morphology of Euphorbia was compared with that from latex of other genera of the Euphorbiaceae. These in–depth analyses of laticifer plastids demonstrates the applicability of starch grain morphology for interpreting the progressive evolution of the nonarticulated laticifer as a cell type within the genus Euphorbia.     

元江干热河谷肉质多利灌丛的研究

以内质多刺植物霸王鞭(Euphorbia royleana)和仙人掌(Opuntia monacantha)为特征的具有荒漠植被景观的元江干热河谷肉质多刺灌丛是一种特殊的次生植被,是在近代原生植被的强烈破坏下,栽培逸生的霸王鞭和仙人掌在局部特别千热土薄多石之处发展而形成的。该群落外貌和结构特殊,可初步定为一个群丛,下分两个亚群丛。在种类组成上,该群落与热带亚洲干早植物区系联系密切,在区系起源上具有古南大陆残余背景,在群落形成和发展上又与人为活动相联系。     

Current distribution and spreading of Euphorbia davidii (E. dentata agg.) in Europe

Of the Euphorbia dentata aggregate, both E. dentata and E. davidii have been reported from Europe. A revision of herbarium and published materials, however, indicates that only E. davidii can be confirmed in Europe. Although known in Europe since 1968, most records are from the 1990s. There are 46 known populations scattered throughout the continent, in Russia, Ukraine, Moldova, Romania, Bulgaria, Hungary, Italy, Belgium, Switzerland and France. Most populations are small and restricted to railway areas; however, the species can also invade agricultural fields. Due to its wide distribution, the growing number of recently established populations, and its invasive ability, special attention should be paid to changes in distribution and population sizes in Europe.     

EVOLUTION OF THE LATICIFER IN EUPHORBIA AS INTERPRETED FROM STARCH GRAIN MORPHOLOGY

The morphology of plastid starch grains from several succulent and nonsucculent species of Euphorbia was examined in parenchyma and in non-articulated laticifiers. Several classes of grains were identified: small oblong-round, rod, somewhat osteoid, osteoid, lobed osteoid, discoid, and round grains. Parenchyma possessed only small oblong-round grains, whereas grains of different morphology were present in laticifers. Different species of this genus can be characterized by the morphology of the large, or mature, starch grains present in the laticifer. The rod-shaped grain, which was somewhat wider at the midregion than at the ends, was present in several nonsucculent forms, E. terracina, E. pulcherrima and E. heterophylla. The somewhat osteoid grain was represented by the succulent species E. viguieri, E. milii, and E. mauritanica, where the mature grains developed somewhat enlarged ends. Grains with much enlarged ends were represented in the succulent species of E. abyssinica, E. pseudocactus, and E. tirucalli. Alteration of the pattern of starch deposition in which several lobes were formed at the ends of the grain has given rise to a lobed osteoid class (E. inconstantia). Lobes also may be formed with greater frequency along the midregion of the grain in this than in other species. Euphorbia lactea had the most complex grain in which lobing was frequent at the ends as well as along the midregion, resulting in a large discoid grain. Subclasses in which grains differed significantly in length between species were evident in all classes containing several species. The average length of grains in any subclass was similar for subclasses between the classes. The study suggests that the elongated grain of the laticifer was derived from the round or oblong grain present in the more primitive parenchymatous cell. Progressive changes in the pattern of starch deposition have given rise to osteoid and discoid grains of increasing morphological complexity which is interpreted to represent trends in laticifer evolution between different species of Euphorbia as reflected by subtle changes for starch deposition within the plastids of this cell.     

Water stress tolerance of shrubs in Mediterranean-type climate regions: Convergence of fynbos and succulent karoo communities with California shrub communities

Mediterranean-type climate regions are highly biodiverse and predicted to be particularly sensitive to climate change. Shrubs of the mediterranean-type climate region of South Africa are highly threatened, and their response to water stress has been comparatively little studied. Resistance to water stress induced xylem cavitation (P(50)) and xylem specific hydraulic conductivity (K(s)) were measured in 15 shrub species from fynbos and succulent karoo communities of South Africa. Species displayed a fivefold variation in cavitation resistance (P(50) of -1.9 to -10.3 MPa) with succulent karoo species displaying greater interspecific variability in P(50) than fynbos species. Principal components analysis (including P(50), minimum seasonal water potential, K(s), and xylem density) showed the response to water stress in fynbos species to be similar to chaparral species from the mediterranean-type climate region of California. The data suggest convergence of community and species-specific water stress "strategies" between these mediterranean-type climate regions with respect to their xylem traits. On the basis of the current study and reported plant death and dieback in these regions, woody species within the fynbos may be more susceptible to climate warming and drying than those within the succulent karoo that appear to be utilizing more diverse xylem strategies in response to water stress.     

The succulent flora of South Africa and Namibia: representation and distribution

Abstract

Taxonomic representation and regional distribution patterns of taxa, life forms, and defence mechanisms of the succulent flora of South Africa and Namibia are quantified and discussed in relation to physical and biotic factors. Habitats are investigated and for each region centres of succulent species richness are pointed out.     

New species of Gondwanamyces from dying Euphorbia trees in South Africa

Gondwanamyces and its Custingophora anamorphs were first described from Protea infructescences in South Africa. Subsequently these unusual fungi were also found on Cecropia in Central America. During an investigation into the decline and death of native Euphorbia trees in South Africa, several fungal isolates resembling the anamorph state of Gondwanamyces were obtained from diseased tissues. In this study these isolates are identified based on morphology and comparisons of DNA sequences. Two previously unknown Gondwanamyces species were identified, both were associated with damage caused by beetles (Cossonus sp.). Inoculation studies showed that the new species of Gondwanamyces are pathogenic on Euphorbia ingens and may contribute to the decline of these trees.     

A contribution to the rust flora (Uredinales) on Aizoaceae in southern Africa

Rust fungi on Aizoaceae in southern Africa have been examined and reported based on 27 specimens collected during a biodiversity study and previously collected herbarium specimens. Eight species including five new species have been recognized, and they are described in detail and illustrated. Together with two additional species in literature, ten species of rust fungi are now recognized on Aizoaceae in southern Africa. Part 223 in the series “Studies in Heterobasidiomycetes” from the Botanical Institute, University of Tübingen.     

Phylogenetics and the evolution of major structural characters in the giant genus Euphorbia L. (Euphorbiaceae)

Euphorbia is among the largest genera of angiosperms, with about 2000 species that are renowned for their remarkably diverse growth forms. To clarify phylogenetic relationships in the genus, we used maximum likelihood, bayesian, and parsimony analyses of DNA sequence data from 10 markers representing all three plant genomes, averaging more than 16kbp for each accession. Taxon sampling included 176 representatives from Euphorbioideae (including 161 of Euphorbia). Analyses of these data robustly resolve a backbone topology of four major, subgeneric clades--Esula, Rhizanthium, Euphorbia, and Chamaesyce--that are successively sister lineages. Ancestral state reconstructions of six reproductive and growth form characters indicate that the earliest Euphorbia species were likely woody, non-succulent plants with helically arranged leaves and 5-glanded cyathia in terminal inflorescences. The highly modified growth forms and reproductive features in Euphorbia have independent origins within the subgeneric clades. Examples of extreme parallelism in trait evolution include at least 14 origins of xeromorphic growth forms and at least 13 origins of seed caruncles. The evolution of growth form and inflorescence position are significantly correlated, and a pathway of evolutionary transitions is supported that has implications for the evolution of Euphorbia xerophytes of large stature. Such xerophytes total more than 400 species and are dominants of vegetation types throughout much of arid Africa and Madagascar.     

New herbaceous and woody species of Euphorbia (Euphorbiaceae) from Somalia

A small prostrate herb, Euphorbia salsicola , a woody shrublet with curious tubers, E. scatorhiza , and a small tree with decorative bracts, E. thulinii , are described as new species of Euphorbia. Within subgenus Lyciopsis the morphological variability of E. cuneata in Somalia is discussed and a new subspecies cretacea is described. E. gypsophila , a closely related but distinct species found only on gypsum is also described as new, together with E. dunensis , a shrublet from the coastal dunes and E. tripartita , another shrub in the same subgenus related to E. matabelensis. As far as present records show, all the new taxa are endemic in Somalia.     

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.