Plant Modifications PDF

Plant Modifications  1. Roots Food-storage roots: in certain plants the roots are enlarged and store large quantities of starch and other carbohydrates.  Some food-storage organs, such as those of carrots, beets, turnips, and radish, are actually a combination of root and...

Plant Modifications  1. Roots Food-storage roots: in certain plants the roots are enlarged and store large quantities of starch and other carbohydrates.  Some food-storage organs, such as those of carrots, beets, turnips, and radish, are actually a combination of root and stem.  Aerial root: in English ivy, the stem climbs with the aid of adventitious roots that arise along the sides of the stem.  Velmane roots: of orchids aid in the absorption of rain water or in preventing loss of moisture from root. Photosynthetic roots: The aerial roots of orchids as they are exposed to the light. Prop roots: in corn produced toward the base of the stems, support the plants in high wind. A banyan (Ficus) tree with many large prop roots that have developed from the branches. Propagative root: roots are able to produce plantlets, which is a means of asexual reproduction. Pneumatophore: roots of plants that grow in swamps or mangles, which are able to grow up, above the water to promote gas exchange. Contractile roots: roots pull bulbs and corms deeper into the soil until an area of relatively stable temperature is reached. Parasitic roots: dodders and broomrapes have no chlorophyll (necessary for photosynthesis). They parasitize their host plants via somewhat rootlike projections called haustoria. Root nodules: numerous small swellings can be seen along the roots of Legume plants contain bacteria (nitrogen- fixing bacteria) that supplement the plant’s nitrogen supply.  2. Stems Stems are, in certain species, modified for functions other than support (of the leaves) and conduction of water and sugars between leaf and root. Some of these modifications include: Cladophyll: flattened stem that resembles a leaf. Rhizome: an underground, horizontal stem; often a means of colonization of neighboring soils or vegetative (asexual) reproduction as portions of rhizome become fragmented. Succulent stem: a stem swollen with water‐storage tissue. Stolon or Runner: more or less horizontal stems that are also called runner, differ from rhizomes in growing above ground, generally along the surface; they also have longer internodes. Thorn: a pointy tip of a stem or pointy lateral (branch) stem. Tuber: swollen, fleshy, underground storage stem, does not necessarily have a defined orientation. The leaves on the tuber are typically reduced to small scales and may be very difficult to see. Tendrils: slender, coiling structure, used for support, these are specialized stems in grape.  3. Leaves Some common modified leaf include:  Bracts: leaves are found at the basis of flowers or flower stalk. In some plants such as the Christmas flower (poinsettia), these are brightly colored that surround the small flowers make up for the absence of petals. Propagative leaves: leaves that produce meristematic regions on margin that produce plantlets asexually. Scale: very small, thin, and non‐photosynthetic leaf; often on subterranean stems such as rhizomes, or the “bud scales” of winter buds on trees and shrubs. Spine: a sharp, pointy leaf. Succulent Leaf: a leaf swollen with water‐storage tissue. Tendrils: slender, coiling structure, used for support, modified from leaf or leaflet in plants such as peas. Variegation: the appearance of differently colored zones on a leaf. Typically, where a green leaf blade is interrupted by white patches or stripes.  4. Shoots (stems plus leaves). Examples of whole shoots that are modified include flowers, bulbs, and corms. Bulb: usually a subterranean shoot with a very short stem and tightly packed succulent leaves. Adventitious roots grow from the bottom of the stem. Corm: a subterranean shoot consisting of a short, but swollen stem and dry and papery or membranous leaves. Adventitious roots are produced at the base. Flower: a determinate shoot with modified leaves, some of which bear sporangia.  Some plants are armed and dangerous.  Prickle: epidermal outgrowths that project from the epidermis of some organ, rather than being a modification of the entire organ. Spine: a leaf modified into a hard, prickly structure. Stipular spines: where the two paired stipules at the base of a leaf or on the stem at the point of leaf attachment are modified into a hard, prickly structure. Thorn: a stem (or multiple stems through branching) modified into a hard, prickly structure. Examine the plant specimens provided. Record the name and identify the modification(s) present. There may be multiple modifications present for each plant. Answer the question associated with the specific plant, if applicable: Number Name Modification(s) Answer to Question: