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These roots have some ability to absorb water and nutrients, but their main function is transport and to provide a structure to connect the smaller diameter, fine roots to the rest of the plant. Contractile roots: roots that pull bulbs or corms of monocots, such as hyacinth and lily, and some taproots, such as dandelion, deeper in the soil ...
In some species contractile roots are produced in response to fluctuating soil temperatures and light levels. In such species, once the corm is deep enough within the soil where the temperature is more uniform and there is no light, the contractile roots no longer grow and the corm is no longer pulled deeper into the soil.
Contractile-roots or Pull-roots – Haptera – root-like projections found in macroalgae or lichens that anchor the organism to a rocky substrate. Protective functions – Root-thorns – Reproductive roots – These roots contain root-buds and actively take part in shoot-regeneration, and thus in vegetative reproduction.
Lilioideae genera are relatively homogeneous and distinct from the other two Liliaceae subfamilies (Calochortoideae and Streptopoideae).They are perennial herbaceous flowering plants that are mainly bulbous (Lilieae) with contractile roots, but may be rhizomatous (Medeoleae).
With these, the bulb grows naturally at some depth in the soil, and each year the new stem puts out adventitious roots above the bulb as it emerges from the soil. These roots are in addition to the basal roots that develop at the base of the bulb, a number of species also produce contractile roots that move the bulbs deeper into the soil. [6]
The roots of the lowermost corm in a chain are contractile roots and drag the corm deeper into the ground where conditions allow. The chains of corms are fragile and easily separated, a quality that has enabled some species to become invasive and difficult to control in the garden.
The corms produce fibrous roots, and contractile roots which adjust the corms depth in the soil, which may be pulled as deep as 20 centimetres (8 in) into the soil. [4] [5] The roots appear randomly from the lower part of the corm, but in a few species, from a basal ridge. [6]
Of the fifteen genera within the Liliaceae, the ten genera of the Lilioideae subfamily form one morphological group that is characterised by contractile bulbs and roots, and a Fritillaria-type embryo-sac (megagametophyte with four megaspores).