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Root tubers are perennating organs, thickened roots that store nutrients over periods when the plant cannot actively grow, thus permitting survival from one year to the next. The massive enlargement of secondary roots typically represented by sweet potato have the internal and external cell and tissue structures of a normal root; they produce ...
Stolons growing from nodes from a corm of Crocosmia. A stem tuber is a thickened part of a rhizome or stolon that has been enlarged for use as a storage organ. [10] In general, a tuber is high in starch, e.g. the potato, which is a modified stolon. The term "tuber" is often used imprecisely and is sometimes applied to plants with rhizomes.
A geophyte (earth+plant) is a plant with an underground storage organ including true bulbs, corms, tubers, tuberous roots, enlarged hypocotyls, and rhizomes.Most plants with underground stems are geophytes but not all plants that are geophytes have underground stems.
In some species (e.g. Cyclamen coum) roots come from the bottom of the tuber, suggesting that it is a stem tuber; in others (e.g. Cyclamen hederifolium) roots come largely from the top of the tuber, suggesting that it is a root tuber. [6] As an example of a combination, juno irises have both bulbs and storage roots. [7]
Tubers develop from either the stem or the root. Stem tubers grow from rhizomes or runners that swell from storing nutrients while root tubers propagate from roots that are modified to store nutrients and get too large and produce a new plant. [22] Examples of stem tubers are potatoes and yams and examples of root tubers are sweet potatoes and ...
Since the hypocotyl is a region between the stem and the roots, such tubers are variable in their anatomy and growth habits. Thus the roots of Cyclamen graecum grow from the base of the tuber, suggesting it is a stem tuber, whereas those of Cyclamen hederifolium mostly grow from the upper surface of the tuber, suggesting it is a root tuber. [10]
The largest known lignotubers (also called "root collar burls") are those of the Coast Redwood (Sequoia sempervirens) of central and northern California and extreme southwestern Oregon. A lignotuber washed into Big Lagoon , California, by the full gale storm of 1977 was 41 ft (12 m) in diameter and about half as tall and estimated to weigh 525 ...
Those growing from the bottom of the corm are normal fibrous roots formed as the shoots grow, and are produced from the basal area at the bottom of the corm. The second type are thicker layered roots called contractile roots that form as the new corms are growing. They pull the corm deeper into the soil.