In botany , annual or (summer) annual plants ( Latin annus , year) are herbaceous plants that only have one vegetation period from the germination of the seed to the development of the entire plant, formation of the flower and fertilization to the fruit ripening of the new seed need and die after the maturity of the seed in the same vegetation period (dry up or rot), whereby this vegetation period can be limited by the onset of frost as well as drought.
From a horticultural point of view and in the narrower sense, an annual plant is a short-lived plant that only blooms for one summer and dies after seed formation. This clearly distinguishes them from the biennial and perennial plants. Typical annuals include:
Plants that are perennial in their home country, but do not survive winter in the temperate latitudes due to the climate (frost), are also referred to as annuals or more horticulturally correct than annuals . These include, for example, the cultivated forms of the Tagetes .
Annual or (summer) annual describes the flowering behavior of plants that flower in the same cultivation period (examples: lettuce, all summer flowers). This means at sowing or planting in the spring usually flower and seed in summer and autumn. As the seeds ripen, the plant exhausts itself and dies. As Annuellenflur an inventory of (predominantly) annual plants is accordingly referred to.
Differentiation from two-year and multi-year
Biennial or winter annual plants, on the other hand, need an intermittent cold stimulus in order to bloom. They therefore usually do not bloom until the following spring and the seeds ripen again in summer. Examples are numerous vegetables such as leeks or cabbage ; these plants also die when the seeds ripen.
In the case of "perennial" plants, a distinction must be made as to whether this term is used in the strictly botanical or horticultural sense: Perennial plants in the botanical sense namely die after several years of growth, sometimes for decades, completed by a one-off flowering and seed maturity, as well as and two-year-olds completely, perennial plants in the horticultural sense, on the other hand, not necessarily: they also need a cold stimulus to form flowers, but may remain alive after flowering and seed ripening (for which the term “persistent” is used in botany ).
Differences in the structure of annual and perennial plants
Structure and lifespan of plants are u. a. Adaptations to the seasonally changing climate (temperature, availability of water).
Annual plants (annuelle) survive the period without vegetation, namely the "physiological dry periods" of winter frost (overwintering) as well as summer drought in steppes and desert areas ("oversommerization"), protected as dormant embryo in the seed. Annual plants are accordingly therophytes , for which it is characteristic that they neither lignify nor form perennial organs such as rhizomes , tubers or bulbs, i. H. the plant body dies completely at the end of the growing season.
Biennial, perennial and perennial plants, on the other hand, have persistence organs that can withstand hostile environmental influences (frost, drought) and in which the plant body is, at least partially, preserved. According to their structure, these plants can be differentiated as follows:
- Trees , so all the trees and shrubs that have a layer of dead tissue (bark) that the underlying, regenerating tissue (cambium) protect; their renewal buds are at least 50 cm above the ground.
- Adapted to snowy winters, half and dwarf shrubs have their renewal buds in the range 10 - 50 cm above the ground, where they are protected in winter by the insulating layer of snow. Many high mountain plants use this overwintering technique, e.g. B. the silver arum (Dryas) or snow heather (Erica). Often, heavily branched, woody, dense plant bodies with green plant parts on the outside (rosette plants) are formed.
Surface plants (hemicryptophytes) have their renewal buds directly on the surface of the earth and are protected by direct contact with the ground. They often form dense clumps to protect the buds. Typical examples are winter cereals, perennial grasses or perennials with aboveground runners (e.g. wild strawberries). The above-ground parts of the plant die off and thus protect the buds.
This also includes the biennial plants, which form the plant body with storage substances in the first year. They therefore often have thickened roots or sprouts (e.g. kitchen onions, carrots, dandelions).
- Plants that sprout from the earth (cryptophytes, geophytes) keep their buds hidden under the earth and are therefore well protected. Typical examples are the bulbous and tuberous plants (tulips, crocuses, etc.), but also those perennials that have their hibernating buds on underground runners.
( once giving birth )
( annual )
|annual||only one continuous vegetation period until flowering and seed formation, then withering||herbaceous|
|bienn / winter annual ( two years )||biennial||two vegetation periods separated by a cold or dry period until flowering and seed formation, then withering|
( perennial )
|perennial||More than two vegetation periods separated by cold or dry periods until flowering and seed formation, then withering||herbaceous ( perennial ) or woody ( subshrubs , shrubs , trees , vines )|
( persistent )
|multiple flowering and seed formation without subsequent death|
- Peter Sitte , Elmar Weiler , Joachim W. Kadereit , Andreas Bresinsky , Christian Körner : Textbook of botany for universities . Founded by Eduard Strasburger . 35th edition. Spektrum Akademischer Verlag, Heidelberg 2002, ISBN 3-8274-1010-X .