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From Wikipedia

Herbaceous plant

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.

Aerial stem modification

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.

From Yahoo Answers

Question:And please also give an example.

Answers:Perennials can be herbaceous and die down to their crown during their dormant period or they can be woody and retain a large exposed structure even while dormant. The function of the stems in both cases is to provide vertical space to transport water & sap via vascular tissues to the transpiring photosynthetic organs (leaves) and the reproductive organs (cones or flowers) from the foraging roots. Woody stems often have the additional function of spatial array. They have a branching pattern in order to display their leaves over as dispersed a space as possible in order to maximized their exposure to sunlight while minimizing water loss. Stems provide height and spread so plants can seek sunlight more efficiently without shading out their own lower leaves. Herbaceous or deciduous perennials that die down each year are mint, peony, hosta, iris, and most grasses. Woody herbaceous herbs are thyme, sage, rosemary and lavender. Shrubs like oleander or rhododendron, plus palms, cactus, rattan, or bamboo are all woody perennials.

Question:does the latter strictly apply to plants in their native environments? but doesn't the average perennial also die down at a certain time of year before flowering again the next?

Answers:The herbaceous perennials typically die back to the ground each year. The portions underground stay alive, ready for the next growing season. A woody perennial has living portions that stay exposed above ground throughout the dormant season. Even if the leaves turn brown and fall off, we know that the twigs and branches are still alive because the leaves regrow when the growing season returns. This growth habit is maintained even outside of the 'native' habitat. Consider tulips or peonies as examples. Growing instructions usually say to clean out spent leaves before the new growth emerges. This not only keeps the garden looking good but can also reduce disease. The diseases evolved to take advantage of the 'natural' habitat of piled up dead stems and leaves. It is good that you have further questions to these answers. Herbaceous is more of a 'description' of this growth habit than the 'definition' of any plant family. A description is fuzzier than a definition. You are smart to ask for a more definitive explanation.

Question:I've googled this question, looked it up on several websites, looked through my textbook, found nothing. All I could find is that the limit for a woody stem's growth is greater. Some people said it was photosynthesis, but don't both go through photosynthesis? & this one person said something about stem propagation..Idk.

Answers:Herbaceous stems can perform photosynthesis, they're green because they contain chloroplasts, woody plants *typically* do not, but the level of photosynthesis is pretty minimal compare to the leaves. However, the only photosynthesizing portion of cacti are the stems and cacti are herbaceous so there is that exception. Also, yes there are more cells capable of redifferentiating into meristematic cells in herbaceous stems so they do propagate more easily.



From Youtube

What's the difference between embyonic and adult stem cells? :A 10 minute discussion on the difference between embryonic and adult stem cells. Focus is on the use of mesenchymal stem cells.

Irv Weissman: Differences between Adult and Embryonic Stem Cells :The simple term "stem cell" actually refers to many different types of cells. The tissue-specific stem cells, or adult stem cells, replenish tissues throughout our lives. Embryonic stem cells exist only briefly in early development before tissues begin to form. Irv Weissman discovered the first tissue stem cells and has helped develop new treatments for disease based on these cells. Weissman has CIRM grant to push embryonic stem cells to form blood and heart muscle stem cells, which could be powerful tools for treating diseases of the heart or blood system. Weissman is Director of the Stem Cell Biology and Regenerative Medicine Institute, Virginia & DK Ludwig Professor for Clinical Investigation in Cancer Research, and Professor of Developmental Biology at the Stanford University School of Medicine.