Sap: fluid content of the xylem, sieve elements of the phloem and the cell vacuole.
Saprophyte: a plant that feeds on dead organic matter.
Sarcotesta: fleshy testa.
Scale: reduced leaves that are usually sessile and seldom green; sometimes epidermal outgrowths if disc-like or flattened.
Scarification: scratching of seed coverings to allow gas exchange and water uptake to enhance germination.
Scurfy: clothed in bran-like scales, eg. fruit of sapodilla.
Seed coat: the outer protective layer of a seed that develops from the integument of the ovule, testa.
Senescence: an active developmental process in which cellular structures and macromolecules are broken down and translocated away from the senescing organ (typically leaves) to actively growing regions that serve as storage sinks.
Sepal: one of the parts of a calyx or outer set of flower parts; may be separate or united to another sepal.
Scion: part of a plant which will be budded or grafted onto a rootstock.
Serrate: having sharp saw-like teeth pinted towards the apex.
Sessile: without a stalk.
Sieve elements: phloem cells that conduct sugars and other organic materials from their sites of synthesis to other areas throughout the plant.
Simple fruit: one that ripens from a single ovary.
Spadix: spike with a thickened fleshy axis eg coconut palm.
Spathe: large bract at the base of a spadix, enclosing it (at least initially) as a sheath.
Spike: type of inflorescence having sessile flowers on a long common axis.
Sport: an unusual vegetative form resulting from a mutation or somatic segregation; may be part or all of a plant.
Spur: short stubby lateral branches that grow from the branches of several fruiting species and produce fruits for 2-4 years, eg apples and peaches.
Stamen: sporophyll within the flower; in angiosperms, the floral organ that bears pollen.
Staminate: having pollen-bearing stamens only, on flowers or inflorescences or individual plants of a dioecious species; male.
Staminode: an aborted or rudimentary stamen in which the anther does not develop and remains sterile.
Stem cells: uncommitted slowly dividing initial cells that produce all the cells in the meristem and thus all the cells in the entire plant.
Stenospermocarpy: the production of aborted or incompletely developed seeds following fertilization, with subsequent normal fruit development., eg some varieties of seedless grapes.
Stigma: pollen-receptive part of a pistil, often enlarged and sticky, usually at the tip of the style.
Stipule: one of a pair of lateral appendages at the base of a leaf petiole.
Stolon: large, indeterminate underground stem that produces roots at intervals capable of giving rise to a new plant.
Stoma: microscopic pore in leaf epidermis surrounded by a pair of guard cells. They regulate the gas exchange (water, oxygen and carbon dioxide) of leaves by controlling the dimension of the stomatal pore; mostly on the under side in dicots and conifers but both with monocots.
Stratification: moist, cold storage.
Style: the narrow upper part of ovary that supports the stigma.
Suberin: a complex of fatty substances present in the wall of cork tissue that waterproofs it and renders it more resistant to decay.
Suckers: many stems arising from the base of a tree or shrub and gradually spreading the diameter of the basal area.
Superior ovary: an ovary with the flower parts growing from below it.
Surfactant: a detergent, adjuvant or other surface-active agent that enhances penetration and action of applied chemicals.
Suture: pre-detemined line along which a carpel of a dehiscent fruit opens.