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Roots of Vicia with white root nodules visible. Cross-section through a root nodule of Vicia observed through a microscope. Biological nitrogen fixation (BNF, performed by the organisms called diazotrophs ) is a very old process that probably originated in the Archean eon when the primitive atmosphere lacked oxygen .
Roots with a diameter less than 0.5 millimeters have been termed 'very fine roots'. [2] [12] Because fine-root traits [13] like diameter vary by species, and research examining the function of different root sizes in different species is limited, diameter-based classes of fine roots are mostly arbitrary and complicate cross-species comparisons.
Pea (pisum in Latin) is a pulse, vegetable or fodder crop, but the word often refers to the seed or sometimes the pod of this flowering plant species. Carl Linnaeus gave the species the scientific name Pisum sativum in 1753 (meaning cultivated pea).
Adventitious roots arise out-of-sequence from the more usual root formation of branches of a primary root, and instead originate from the stem, branches, leaves, or old woody roots. They commonly occur in monocots and pteridophytes, but also in many dicots , such as clover ( Trifolium ), ivy ( Hedera ), strawberry ( Fragaria ) and willow ( Salix ).
The tree is well suited to intense heat and sunlight, and its dense network of lateral roots and its thick, long taproot make it drought tolerant. The dense shade it provides slows the evaporation of surface water and its root nodules promote nitrogen fixation , a symbiotic process by which gaseous nitrogen (N 2 ) from the air is converted into ...
Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium. [8] In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual ...
Root vegetables are underground plant parts eaten by humans or animals as food. In agricultural and culinary terminology, the term applies to true roots such as taproots and tuberous roots as well as non-roots such as bulbs , corms , rhizomes , and stem tubers .
Optimum temperatures for tree root growth range between 10 °C and 25 °C in general [98] and for spruce in particular. [99] In 2-week-old white spruce seedlings that were then grown for 6 weeks in soil at temperatures of 15 °C, 19 °C, 23 °C, 27 °C, and 31 °C; shoot height, shoot dry weight, stem diameter, root penetration, root volume ...