|
The Heliantheae are the third-largest tribe in the sunflower family (Asteraceae). With some 190 genera and nearly 2500 recognized species, only the tribes Senecioneae and Astereae are larger. The name is derived from the genus ''Helianthus'', which is Greek for sun flower. Most genera and species are found in North America and South America, particularly in Mexico. A few genera are pantropical. Most Heliantheae are herbs or shrubs, but some grow to the size of small trees. Leaves are usually hairy and arranged in opposite pairs. The anthers are usually blackened. The above statements about the size and distribution of the tribe apply to a broad definition of Heliantheae, which was followed throughout the 20th century. Some recent authors break the tribe up into a dozen or so smaller tribes. ==Uses== Commercially important plants in the Heliantheae include sunflower and Jerusalem artichoke. Many garden flowers are also in this group, such as ''Coreopsis'', ''Cosmos'', ''Echinacea'', ''Rudbeckia'', and ''Zinnia''. In addition to the benefits brought by the group, some are also problematic weeds. Species of ''Ambrosia'' (ragweed) produce large quantities of pollen. Each plant is reputed to be able to produce about a billion grains of pollen over a season, and the plant is wind-pollinated. It is highly allergenic, as the greatest pollen allergen of all pollens, and the prime cause of hay fever. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Heliantheae」の詳細全文を読む スポンサード リンク
|