(1) The root hairs are found in (2)the zone of absorption (felszívási övezet). Below that is the (3) zone of elongation (megnyulási övezet), where the cells get longer, and the (4) apical meristem, where the cells divide. The apical meristem is protected by the (5) root cap (gyökersüveg), which is tough and slimy.
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| Cross-section of a root |
Looking at a root in cross-section, we can not that the xylem and phloem are in separate vascular bundles, separated by the vascular cambium. The epidermis around the edge of the root is not water-proof, but the endodermis, which surrounds the vascular tissue, is covered in a waxy substance called suberin, which makes it waterproof and helps regulate the movement of water, ions and hormones into and out of the vascular system. Lateral roots will grow out of the pericycle. The cortex is formed of parenchyma cells.
All roots have the function of anchoring the plant and absorbing water and minerals.
Root modifications:
-for food storage, eg. tubers (gumók)
- aerial roots from the stem eg. used for clinging in ivy
- prop roots from the stem eg. help corn to stand
2. Stems
Image from: users.rcn.com
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| Cross-sections of herbaceous dicot and monocot stems |
Cross-section of a woody stem:
Image from: hrsbstaff.ednet.ns.ca
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- annual growth rings (in temperate climates): The light coloured region is the result of the cells being large and thin-walled, since they are formed in the spring when water is plentiful. The dark coloured region is formed from smaller, thick-walled cells which are formed in the summer, when there is less water. In winter there is no growth.
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The functions of the stem include: support, transport of water and minerals to the shoots (xylem) and organic compounds from the sites of photosynthesis to the areas where they are needed (phloem), as well as photosynthesis if the stem is herbaceous.
Stem modifications:
-food storage, eg. rhizome (gyöktörzs), corms and bulbs (hagyma), tubers (gumó)
- spreading, eg. stolons (indák)
3. Leaves
Image from: southtexascollege.edu
Note that the veination of the leaves is different. In dicots the veins are branched, whereas in monocots they are parallel.
Leaf types:
Leaves can be simple or compound, deciduous (lombhullató) or evergreen.
Image from: www-saps.plantsci.cam.ac.uk
Looking at a leaf in cross-section:
Image from: kentsimmons.uwinnipeg.ca
Functions of the leaf include photosynthesis, transpiration (növényi párologtatás) through the stomata (bordered by guard cells in figure) and gas exchange (also through the stomata).
Leaf modifications:
- succulents (for water storage)
Image from: florico.com
- spines (to decrease water loss and reduce herbivore damage)
Image from: nazflora.org
Image from: aaref.com
- tendrils (for climbing)
Image from: ars.usda.gov
- food storage (bulbs)
- food catching (eg. Venus flytrap)
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- food catching (eg. Venus flytrap)
Image from: tealco.net
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