Underground stem

Article

November 28, 2021

Underground stems (subterranean stems) are stems that are normally underground and have properties adapted to the underground (right figure). Some are located just below the surface of the earth and some extend deep underground, and some are located in the ground below the bottom of the water, such as Hass. On the other hand, stems that extend above the surface of the earth are called aboveground stems (aerial stems, epigeal stems, terrestrial stems). Rhizome is similar to roots in that it is underground, but can usually be distinguished by the addition of leaves (such as scaly leaves) (often leaving traces) and the absence of root caps and root hairs. Rhizome is often classified into rhizome, corm, tuber, and bulb according to its morphology and structure. Like the roots, the rhizomes play a role in fixing the plant to the soil, and the rhizomes usually give rise to roots (adventitious roots). In addition, rhizomes store nutrients and become durable structures during unsuitable growth periods (winter, etc.), after which new above-ground parts are formed, and many are used to separate from the mother and become new individuals (vegetative propagation). .. Among the rhizomes, there are examples of being used for food and medicine such as potatoes, onions, garlic, taro, and turmeric.

Various rhizomes

Rhizome is a general term for underground stems and is classified into various types with different morphologies and functions. However, these divisions are convenient and not always clear, and bulbs may be included in tubers. Also, rhizome and rhizome may be synonymous.

Rhizome

The rhizomes, tubers, and rhizomes that do not show specialization, such as the following bulbs, tubers, and rhizomes, are collectively called rhizomes (root stock) (see the figure below). Rhizome such as Sugina (Tokusa), Warabi (Umbelliferae), Dokudami (Lizard tails), Giboushi (Asparagus family), Susuki (Rice family), Wasabi (Abrana family), Swiba (Polygonaceae), Shishiudo (Umbelliferae) Plants with rhizomes are called rhizome plants. Also, the stems that crawl on the bases (trunks, etc.) found in epiphytes such as Lepisorus thunbergii are not in the ground, but are customarily called rhizomes. Rhizome may be classified as follows according to its position and extension direction. A rhizome that extends horizontally in the ground is called a horizontal rhizome (see the figure below). In particular, horizontal rhizomes with long internodes are also called creeping rhizomes (stoloniform rhizome). Such horizontally extending rhizomes may be unclear from the creeping stems (repent stems) that crawl on the surface of the earth, especially if they are just below the surface of the earth. On the other hand, a rhizome that extends vertically in the ground is called an upright rhizome (see the figure below). A rhizome having only one of the above rhizome types is called a simple rhizome. On the other hand, two or more types of rhizomes (eg, crawling rhizomes and upright rhizomes), or rhizomes with special rhizomes such as tubers (see below) are called compound rhizomes. Of the rhizomes, those that are in the ground from the beginning are called primary rhizomes. On the other hand, what was on the ground moved into the ground and became a rhizome is called a secondary rhizome. Those with remnants of ordinary leaves and flower stems indicate that they were aboveground stems, indicating that they are secondary rhizomes. Secondary rhizomes are found in Heloniopsis orientalis (Melanthiaceae) and Humulus lupulus (Hempaceae). The rhizomes that form propagules in the nodes are called coral-shaped rhizomes and are found in horsetails (horsetails).

Corm

Formed at the base of the rhizome

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