Sphingolipid - A type of complex lipid having long-chain amino acid alcohol e.g., sphingosine. It is joined by an amide linkage to a long-chain fatty acid. It is important as membrane components in both animal and plant cells. In yeasts and higher plants, amino alcohol is usually phytosphingosine.

Spike - Refers to a racemes inflorescence in which flowers are sessile and are brone on an elongated axis as in wheat.

Spikelet - One of the units of the inflorescence of a grass. It is having a central rachis which is bearing one or more sterile glumes at the base, followed by one or more flowers. Each enclosed between a flowering glume and palea. All the parts become crowded together.

Spindle - The axially differentiated crystalline ('fibrous') part of the cytoplasm within which there occurs the orientations of the centromeres of the chromosomes during metaphase and anaphase. It is com posed of longitudinally orientated protein molecules. Movement of the chromatids apart during anaphase may occur due to pulling by contractile fibers in the spindle.

Spindle Attachment - Refers to the position of the centromere.

Spindle Fibre - The orientated protein molecules of the spindle.

Spine - The end of a branch or leaf which has become rounded in se ction, and is hard and sharply pointed.

Spiral - Refers to a coil of the chromosome, chromatid, or chromosome-thread a mitosis or meiosis.

Spiral Cell, Spiral Tracheid (E), Spiral Vessel - Used for the cell, tracheid (e), or vessel in which the secondary wall is laid down in the form of spirally arranged thickened.

Spiral Thickening (helical thickening). Refer to a type of secondary wall patterning found in treachery elements in which secondary wall has been laid down in a helical pattern. This pattern, like annular thickening, permits further elongation of cell and therefore, occurs in tissues such as protoxylem which develop in young organs and continue elongation.

Spirillium - Cork-screw shaped bacterium, some of which are motile having terminal flagella.

Splint Wood - Wood in which the living cells have been scattered throughout.

Spodogram - Refers to the preparation of the ash of a portion of a plant, especially- a woody portion, used in investigation of structure.

Spongioplasm - Describing the more viscid constituents of cytoplasm, forming a thread work.

Spongy Layer, Spongy Mesophyll, Spongy Parenchyma, Spongy Tissue. A loosely constructed layer of irregularly shaped cells which are separated by large intercellular spaces. It lies just above the lower epidermis of a dorsiventral leaf and has chloroplasts.

Spontaneous Generation - A theory which postulates that living organisms are generated spontaneously and directly from non-living matter. Theory was conclusively disproved in 1862 by Louis Pasteur. The theory is different from the theory of abiogenesis and origin of life.

Sporangiophore - Of fungi, hyphae bearing one or more sporangia, sometimes, morphologically distinct from vegetative hyphae.

Sporangiospore - A spore, especially a non-motile spore which is formed within a sporangium.

Sporangium - The structure having asexual spores.

Spore - An asexual reproductive body that may be unicellular or multicellular, and produced by haploid or diploid generations. Spore production is a phase in a life-cycle which is inserted between two sexual phases (if present).

Spore Membrane, Spore Wall - The firm membrane which is surrounding contents of a spore.

Spore Mother Cell - A diploid cell giving rise to four haploid spores by meiosis.

Sporocarp - (1) A fmit-body of the fungi.
(2) A multi-cellular structure in which spores are found.
(3) A spore containing structure of the, Marsiliaceae and Salviniace.

Sporocyte. A spore mother-cell.

Sporogenesis - Describing the process by which spores are formed. Process of formation of microspores and megaspores are known as microsporogenesis and megasporogenesis respectively.

Sporophore - Of fungi, a general term used for any structure producing and bearing spores,

Sporophyll - A leaf bearing sporangia. It may resemble an ordinary leaf, except for the sporangia,. e.g. in the ferns, or it may be highly modified, e.g., the stamens and carpals of flowering plants.

Sporophyte - An individual of the diploid generation of plants that is usually producing spores, and is formed by the union of sexual cells produced by the gametophyte.

Sporoplasm - The spore-producing protoplasm within the epiplasm of a sporanium or ascus.

Sport - Used for an a typical form of an individual, due to mutation or segregation. This term is usually restricted to new forms and is most commonly used in horticulture.

Spur - (Sort Sdoot). (1) A short branch on which flowers and fruits are brone.
(2) The extension of the base of a leaf beyond its point of attachment.
(3) A hollow horn-like extension of a petal, or gamopetallous corolla.

Spurious Dissepiment (False Septum) - A partition in a fruit which is neither an in growth from the edges of the carples, nor an upgrowth from the receptacle.

Spurious Fruit - A group of fruits which are having the appearance of a single fruit.

Spur Pelory - Represents abnormal condition m which all the petals of an irregular flowers develop spurs, so that the flower becomes regular.

Stachyose - Refers to a non-reducing tetrasaccharide which is made up of two galactose and one unit each of glucose and fructose. It occurs in many members of Labiatae, especially the tubes of Stachys tuberifera and in some leguminous plants.