FORRAGICULTURA E PASTAGENS PDF
The Forragicultura e Pastagens Department at IAPAR on Veja grátis o arquivo Cacti. Biology and Uses enviado para a disciplina de Forragicultura e Pastagens Categoria: Outros – 9 – Veja grátis o arquivo Cacti. Biology and Uses enviado para a disciplina de Forragicultura e Pastagens Categoria: Outros – 8 –
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Similar types of taxonomic placement forragicltura can also be resolved at the species level. Presence or absence of a major structural rearrangement is very useful in determining evolutionarily related groups of taxa.
Occurrence of the bp deletion in the intron of the plastid gene rpl16 is useful for including or excluding taxa thought to be related to that clade. Further study of these relationships will forrzgicultura the information base from which more robust hypotheses about columnar cactus evolution and migration in South America can be more reliably made.
This is regrettable because some opuntias are dominant perennials in drylands of the New World or have become weedy invaders elsewhere and spread by grazing habits of livestock Nobel Important food sources are obtained from platyopuntias Russell and Felker Understandably, gardeners generally elected not to cultivate opuntias, which have nasty, irritating glochids and are not easily controlled plants, but now, growing small op- untioids, especially taxa from western South America, has become very popular among cactus enthusiasts.
Perhaps most important, an intensive phyloge- netic analysis for this subfamily is required to evaluate the generic circumscription. A number of morphological transitions pastagnes been hy- pothesized for the opuntioid lineages.
Two in particular are 12 Wallace and Gibson key: Another presumed trend has been a shift in growth habit from upright woody plants shrubs to small trees to shrubby or sprawling clumps, and even evo- lution of the geophytic habit in Pterocactus, in which most plant biomass is subterranean and the aboveground parts are annual shoots.
A factor that contributes considerably to the taxo- nomic confusion within the subfamily is the high level of phenotypic plasticity shown within many opuntioid taxa. Addi- tionally, both polyploidy and hybridization have played a vital role in the evolution of the diversity of these cacti and have also contributed to nomenclatural chaos Benson Columnar ancestor Leptocereeae Pachycereinae Pachycereeae Stenocereinae?
Hypothesized intergeneric relationships within some North American columnar cacti based on analyses of rpl16 intron sequences. Although Opuntioideae present a considerable chal- lenge to the cactus systematist, recent studies have provid- ed much insight into opuntioid evolution.
Some morphologically distinct plants, such as the geo- phytic species of Pterocactus in Argentina or the persistent leaf-bearing species Pereskiopsis and Quiabentia of North and South America, respectively, are more readily distin- guished as segregate genera. But even here, Pereskiopsis and Quiabentia have been lumped into a single genus Hunt and Taylor Studies of seed morphology and other aspects of mi- cromorphology have provided evidence that a complete reevaluation of the generic circumscriptions in the sub- family is warranted Stuppy A basal lineage for the subfamily appears to include the species referable to the genera Austrocylindropuntia and Cumulopuntia, both native to the Peru-Bolivia-Chile Andean regions.
Other clades are the narrowly distributed South American Pterocactus; a clade of Maihueniopsis-Tephrocactus including Puna ; and two clades containing the more widely distributed opuntioids found in both North and South America.