Target 2 of the 2020 Global Strategy for Plant Conservation (GSPC) calls for a comprehensive list of the world's threatened plant species. The lack of such a list is one of the greatest impediments to protecting the full complement of the world's plant species, and work to achieve this has been slow. An efficient system for identifying those species that are at risk of extinction could help to achieve this goal in a timeframe sensitive to today's conservation needs. Two systems that efficiently use available data to assess conservation status were tested against a provisional International Union for Conservation of Nature and Natural Resources (IUCN) Red List analysis to evaluate the native seed plant species of Puerto Rico. It was demonstrated that both systems efficiently identify species at risk, which is a step toward both the GSPC Target 2 and a more comprehensive IUCN Red List for plants. Both systems were effective at identifying plant species at risk, with the New York analysis identifying 98% and the Smithsonian analysis 85% of the plant species considered Threatened in the IUCN Red List. Both analyses to some extent overestimated those plants at risk, but the species identified are all range restricted and, thus, of some conservation interest.
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ABSTRACT.Eleven flavonoid compounds-one C-glycosyl flavone and ten flavonol glycosideswere isolated and identified from leaf material of Cnidoscolus aconitifolius, C. souzae, and C. spinosus. The flavonol glycosides were the galactosides, glucosides, rhamnosides, and rhamnosylglucosides of quercetin and kaempferol, and two triglycosides of the latter flavonol. Cnidoscolus aconitifolius and C. spinosus exhibit considerable chemical variability. The flavonoid data support the inclusion in C. aconitifolius of C. aconitifolius subsp. polyanthus and C. aconitifolius subsp. aconitifolius cv. Chayamansa, "chaya," a plant of some economic importance. The data also suggest that these two taxa originated in the Yucatan region of Mexico.
Metal hyperaccumulators are plants that store heavy metals or metalloids in their leaves, often to concentrations much higher than in the soil. Though most occur exclusively on metalliferous soils, some species are facultative, occurring on both metalliferous and nonmetalliferous soils. Psychotria grandis Sw.(Rubiaceae) occurs from Central America through the Caribbean on many soil types, and hyperaccumulates nickel (Ni) on serpentine soils in several localities. In this study, four Puerto Rican populations of P. grandis – two from serpentine soil and two from non-serpentine soil – were examined to compare Ni accumulation between and within populations. Multiple trees were sampled at most sites, with replicate leaves harvested from each tree. Foliar nickel concentrations were measured by atomic absorption spectrometry. Mean Ni concentration differed significantly among the sites, ranging from <165 µg g–1 on non-serpentine soil to >4000 µg g–1 on serpentine soil. There were also significant differences in Ni concentration among trees within sites, with especially wide variation at one of the serpentine sites known to be geologically heterogeneous. Despite these differences in field-collected leaves, a hydroponic common-garden experiment indicated that the Ni accumulation capacities of the populations were approximately equal. Variation in Ni accumulation between and within these populations in the field is likely to result from variation in Ni availability in the soil.
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