A herbaceous plant (in botanical use simply herb) is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground. Herbaceous plants may be annuals, biennials or perennials.

Annual herbaceous plants die completely at the end of the growing season or when they have flowered and fruited, and they then grow again from seed.

Herbaceous perennial and biennial plants have stems that die at the end of the growing season, but parts of the plant survive under or close to the ground from season to season (for biennials, until the next growing season, when they flower and die). New growth develops from living tissues remaining on or under the ground, including roots, a caudex (a thickened portion of the stem at ground level) or various types of underground stems, such as bulbs, corms, stolons, rhizomes and tubers. Examples of herbaceous biennials include carrot, parsnip and common ragwort; herbaceous perennials include peony, hosta, mint, most ferns and most grasses. By contrast, non-herbaceous perennial plants are woody plants which have stems above ground that remain alive during the dormant season and grow shoots the next year from the above-ground parts – these include trees, shrubs and vines.

Some relatively fast-growing herbaceous plants (especially annuals) are pioneers, or early-successional species. Others form the main vegetation of many stable habitats, occurring for example in the ground layer of forests, or in naturally open habitats such as meadow, salt marsh or desert.

Some herbaceous plants can grow rather large, such as the Musagenus, to which thebanana belongs.

Ariel stem modifications are modifications to the aerial stems, vegetative buds and floral buds of plants which perform special functions. Overview The aerial stems, vegetative buds and floral buds of plants growing in different conditions undergo modifications to perform special functions. These modifications are called "aerial stem modifications'. They include tendrils, thorns, hooks, phylloclade, tuberous stems and bulbils. Tendrils Some weak stemmed plants produce wiry, coiled, sensitive and delicate organs for climbing. They are called tendrils . These may develop from either the axillary bud or the terminal bud of the stem. In Passiflora, the tendrils develop from the axillary bud. In Cissus quadrangularis. And in Vitis vinifera the terminal bud develops into tendrils. Thorns These are hard, woody, pointed structures meant for protection. They are provided with vascular tissue, which may develop from the axillary bud or terminal buds. They control transpiration by reducing the vegetative growth. In Bougainvillae, Punica granatum and Duranta the axillary bud develop into thorns. In Duranta, the thorns are provided with leaves and flowers. In Punica granatum, the thorns bear leaves and branches. In Carissa carundus the terminal bud produces a pair of thorns. They help in protection.