Stems, xylem herbaceous flowers underdevelopment, weak supportive, saying the grass stems. Flower has herbaceous stem, called the herbaceous flowers. Herbaceous flowers in their growth period different lengths, can be divided into annual, biennial and perennial kinds. Annual (A) Annuals flowers? Living on less than one hair of sowing, when development firm, then death. As a string of red, thorn eggplant, Portulaca grandiflora (Egeria purslane) and the like. Biennial (b) biennial flowers? Life span of two years, generally in the autumn sowing, the second year the spring and summer blossom until death. Such as snapdragons, marigolds, pansy like. Perennial (iii) the tip of perennial flowers born more than two years, they have a common characteristic is a permanent part of the underground (underground roots, underground stems), perennial die. But their aerial parts (stems and leaves) but there are two types: some aerial parts to maintain evergreen, such as asparagus, Begonia, tiger palm, etc; some aboveground, is every spring from the underground root Inter sprouted new shoots grow into plants, the dead of winter. Such as peony, canna, dahlia, iris, hosta, tuberose and so on. Perennial flowers, because of their underground parts always maintained the ability to live, so they shall be called perennial flowers category.