伞形科Apiaceae.doc

伞形科 Apiaceae 1-Floral formula Here isthe floral formula for the Apiaceae or Umbelliferae. The flowers may beperfect, but more often they are imperfect, and the plants are then monoecious, dioecious, orpolygamous. The sepals are very tiny inthe Apiaceae, the petals are often curved, the 5stamens within aflower unfold atdifferent times, the style bases enlarge toform the stylopodium that secretes nectar, and the ovary isinferior. 2-Introduction This family iscorrectly called either the Apiaceae orthe older Umbelliferae. Inthe modern context, the family includes agroup ofplants formerly separated asthe Araliaceae. Dr. Stephen Downie has done considerable research onthe systematics ofthis family using molecular methods. Members ofthe Apiaceae occur worldwide. There are about 460 genera and 4,250 species. Most plants of this family that occur intemperate regions are herbaceous, while those inthe tropics are shrubs and trees. 3-Biennial plants Many members ofthe Apiaceae intemperate regions are herbaceous plants —annuals, biennials, and perennials. Many species are biennials, like carrots, that produce leaves and anunderground root the first year, then flower, set seed, and die during the second year 4-Hollow stems Most members ofthe Apiaceae have hollow stems. The stems also have oil tubes that contain fragrant essential oils. This hum graveolens ,dill. 5-Leaves Many members ofthe Apiaceae have pound leaves and sheathing leaf bases. The leaves, aswell asthe stems, also have oil tubes that contain fragrant essential oils. This example hum graveolens ,dill. 6-Daucus carota Acommon plant along roadsides inIllinois isQueen Anne's Lace, Daucus carota. This isthe same species asthe cultivated carrot. This species isabiennial, and these are second year plants that are producing flowers 7-Umbel inflorescence The basic inflorescence type inthe Apiaceae isan umbel. InDaucus carota ,pound umbel. Note the bracts below the inflorescence. 8-Flowers This isasimple umbel inwild parsnip,