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The formation of the seed is the defining part of the process of reproduction in seed plants (spermatophytes). Other plants such as ferns, mosses and liverworts, do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates.
The spermatophytes were traditionally divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetophytes, cycads, [5] ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms, [ 6 ] in particular based on vessel elements .
In most seed plants, especially woody types, the endodermis is present in roots but not in stems. The endodermis helps regulate the movement of water, ions and hormones into and out of the vascular system. It may also store starch, be involved in perception of gravity and protect the plant against toxins moving into the vascular system.
The stem can also be called the culm, halm, haulm, stalk, or thyrsus. The stem is normally divided into nodes and internodes: [2] The nodes are the points of attachment for leaves and can hold one or more leaves. There are sometimes axillary buds between the stem and leaf which can grow into branches (with leaves, conifer cones, or flowers). [2]
Botany is a natural science concerned with the study of plants.The main branches of botany (also referred to as "plant science") are commonly divided into three groups: core topics, concerned with the study of the fundamental natural phenomena and processes of plant life, the classification and description of plant diversity; applied topics which study the ways in which plants may be used for ...
Epiphytic root – This type of root seen in epiphytic orchids. The thick root hangs from the plant's base directly into air. The root is covered with a special, usually 4- to 5-cell layer thick, [12] spongy tissue (called Velamen), which helps the plant to absorb moisture from the atmosphere. Epiphytic orchid have another sort of root, called ...
The uptake of water by seeds is called imbibition, which leads to the swelling and the breaking of the seed coat. When seeds are formed, most plants store a food reserve with the seed, such as starch, proteins, or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated ...
Seed plants, which first appeared in the fossil record towards the end of the Paleozoic era, reproduce using desiccation-resistant capsules called seeds. Starting from a plant which disperses by spores, highly complex changes are needed to produce seeds. The sporophyte has two kinds of spore-forming organs or sporangia.