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2006-09-14 11:51:32 · 5 answers · asked by Linds27*** 2 in Food & Drink Other - Food & Drink

5 answers

Thin hairy stems that support the leaves.

2006-09-14 11:58:43 · answer #1 · answered by EarthStar 5 · 0 0

When buying strawberries, choose only those berries that are bright red and still have their leafy calyx firmly attached. Once the calyx is removed from the berry, ascorbic acid oxidase, an enzyme that destroys vitamin C, is released by the torn cells.

2006-09-14 11:56:24 · answer #2 · answered by Anonymous · 0 0

Ask a Mexican, they pick em all the time at My house.

2006-09-14 11:58:51 · answer #3 · answered by whitetrashwithmoney 5 · 0 0

The cactus... has both, actually.

2016-03-17 21:24:13 · answer #4 · answered by ? 4 · 0 0

stem is the main axis of a vascular plant that is divided into nodes and internodes and has one or more leaves or buds at the nodes. In everyday speech, shoots are often confused with stems. Stems, which are a critical component of shoots, provide an axis for buds, flowers or cones, fruits or seeds, and leaves. Stems are aboveground in many plants but some grow underground. The aerial stem of an adult tree is called a trunk. The dead, usually darker inner wood of a large diameter trunk is termed the heartwood. The outer, living wood is termed the sapwood. The main functions of aerial stems are

Support and elevate leaves, flowers and fruits and keep leaves in the light.
Transport of fluids between the roots and the shoots in the xylem and phloem.
Storage of nutrients
Contents [hide]
1 Specialized stems
2 Stem structure
2.1 Dicot stems
2.2 Gymnosperm stems
2.3 Monocot stems
2.4 Fern stems
3 Economic importance



[edit]
Specialized stems
Stems are often specialized for storage, asexual reproduction, protection or photosynthesis, including the following:

Bulb - a short vertical underground stem with fleshy storage leaves attached, e.g. onion, daffodil, tulip. Bulbs often function in reproduction by splitting to form new bulbs or producing small new bulbs termed bulblets. Bulbs are a combination of stem and leaves so may better be considered as leaves because the leaves make up the greater part.
Cladophyll - a flattened stem that appears leaflike and is specialized for photosynthesis, e.g. asparagus, cactus pads.
Corm - a short enlarged underground, storage stem, e.g. taro, crocus, gladiolus. Corms form many small cormlets.
Rhizome - a horizontal underground stem that functions mainly in reproduction but also in storage, e.g. most ferns, iris
Stolons or runner - is an aboveground, horizontal stem that produces rooted plantlets at its nodes, e.g. strawberry, spider plant.
Thorns - a sharp, stiff modified stem that functions to prevent the plant from being grazed upon, e.g. honeylocust, hawthorn. Spines and prickles have a similar structure and function but are not modified stems. Spines are modified leaves orstipules, and prickles are outgrowths of the epidermis.
Tuber - a swollen, underground storage stem adapted for storage and reproduction, e.g. potato.
[edit]
Stem structure
Stem usually consist of three tissues, dermal tissue, ground tissue and vascular tissue. The dermal tissue covers the outer surface of the stem and usually functions to waterproof, protect and control gas exchange. The ground tissue usually consists mainly of parenchyma cells and fills in around the vascular tissue. It sometimes functions in photosynthesis. Vascular tissue provides long distance transport and structural support. Most or all ground tissue may be lost in woody stems. The dermal tissue of aquatic plants stems may lack the waterproofing found in aerial stems. The arrangement of the vascular tissues varies widely among plant species.

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Dicot stems
Dicot stems with primary growth have a pith in the center with vascular bundles in a distinct ring visible in cross section. The outside of the stem is covered with an epidermis, which is covered by a waterproof cuticle. The epidermis also may contain stomata for gas exchange and hairs. A cortex of parenchyma cells lies between the epidermis and vascular bundles.

Woody dicots and many nonwoody dicots have secondary growth originating from their lateral or secondary meristems: the vascular cambium and the cork cambium or phellogen. The vascular cambium forms between the xylem and phloem in the vascular bundles and connects to form a continuous cylinder. The vascular cambium cells divide to produce secondary xylem to the inside and secondary phloem to the outside. As the stem increases in diameter due to production of secondary xylem and secondary phloem, the cortex and epidermis are eventually destroyed. Before the cortex is destroyed, a cork cambium develops there. The cork cambium divides to produce waterproof cork cells externally and sometimes phelloderm cells internally. Those three tissues form the periderm, which replaces the epidermis in function. Areas of loosely-packed cells in the periderm that function in gas exchange are called lenticels.

Secondary xylem is commercially important as wood. The seasonal variation in growth from the vascular cambium is what creates yearly tree rings in temperate climates. Tree rings are the basis of dendrochronology, which dates wooden objects and associated artifacts. Dendroclimatology is the use of tree rings as a record of past climates.

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Gymnosperm stems
All gymnosperms are woody plants. Their stems are similar in structure to woody dicots except that most gymnosperms produce only tracheids in their xylem, not the vessels found in dicots. Gymnosperm wood also often contains resin ducts. Woody dicots are called hardwoods, e.g. oak, maple and walnut. In contrast, softwoods are gymnosperms, such as pine, spruce and fir.

[edit]
Monocot stems
Vascular bundles are present throughout the monocot stem, although concentrated towards the outside. This differs from the monocot root that has a ring of vascular bundles and often none in the center. The shoot apex in monocot stems is more elongated. Leaf sheathes grow up around it, protecting it. This is true to some extent of almost all monocots. Monocots rarely produce secondary growth and are therefore seldom woody. However, many monocot stems increase in diameter via anamolous secondary growth.

[edit]
Fern stems
Most ferns have rhizomes with no vertical stem. The exception is tree ferns, with vertical stems up to about 15 meters. Stem anatomy of ferns is more complicated that dicots because fern stems often have one or more leaf gaps in cross section. A leaf gap is where the vascular tissue branches off to a frond. In cross section, the vascular tissue does not form a complete cylinder where a leaf gap occurs. Fern stems may have solenosteles or dictyosteles or variations of them. Many fern stems have phloem tissue on both sides of the xylem in cross-section.

[edit]
Economic importance
There are thousands of species whose stems have economic uses. Stems provide a few major staple crops such as potato and taro. Sugar cane stems are a major source of sugar. Maple sugar is obtained from trunks of maple trees. Vegetables from stems are asparagus, bamboo shoots, cactus pads or nopalitos, kohlrabi, Jerusalem artichoke and water chestnut. The spice, cinnamon is bark from a tree trunk. Cellulose from tree trunks is a food additive in bread, grated Parmesan cheese, and other processed foods. Gum arabic is an important food additive obtained from the trunks of Acacia senegal trees. Chicle, the main ingredient in chewing gum, is obtained from trunks of the chicle tree.

Medicines obtained from stems include quinine from the bark of cinchona trees, camphor distilled from wood of a tree in the same genus that provides cinnamon, and the muscle relaxant curare from the bark of tropical vines.

Wood is a used in thousands of ways, e.g. [building material|buildings], furniture, boats, airplanes, wagons, car parts, musical instruments, sports equipment, railroad ties, utility poles, fenceposts, pilings, toothpicks, matches, plywood, coffins, shingles, barrel staves, toys, tool handles, picture frames, veneer, charcoal and firewood. Wood pulp is widely used to make paper, cardboard, cellulose sponges, cellophane and some important plastics and textiles, such as cellulose acetate and rayon. Bamboo stems also have hundreds of uses, including paper, buildings, furniture, boats, musical instruments, fishing poles, water pipes, plant stakes, and scaffolding. Trunks of palm trees and tree ferns are often used for building. Reed stems are also important building materials in some areas.

Tannins used for tanning leather are obtained from the wood of certain trees, such as quebracho. Cork is obtained from the bark of the cork oak. Rubber is obtained from the trunks of Hevea brasiliensis. Rattan, used for furniture and baskets, is made from the stems of tropical vining palms. Bast fibers for textiles and rope are obtained from stems include flax, hemp, jute and ramie. The earliest paper was obtained from the stems of papyrus by the ancient Egyptians.

Amber is fossilized sap from tree trunks; it is used for jewelry and may contain ancient animals. Resins from conifer wood are used to produce turpentine and rosin. Tree bark is often used as a mulch and in growing media for container plants.

Some ornamental plants are grown mainly for their attractive stems, e.g.:

2006-09-14 11:53:28 · answer #5 · answered by Irina C 6 · 0 0

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