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R

Raceme: [Inflorescences] {type} An elongate, indeterminate inflorescence with stalked flowers borne singly along an unbranched main axis or rachis.

Racemose: In the form of a simple or compound raceme; bearing racemes.

Rachilla: This is a side stalk that diverges from the central stalk (rachis) in either a compound leaf (as in ferns) or an inflorescence (as in grasses and sedges)

Rachis: 1) The main axis of a compound leaf above the point of attachment of the lowermost leaflet; a continuation of the leaf stalk or petiole. 2) The main axis of a compound inflorescence above the point of attachment of the lowermost flower; a continuation of the inflorescence stalk or peduncle.

Radially symmetric: [Calyx, Corolla] {symmetry} Divisible into two essentially equal portions along more than one plane.

Raised: [Leaf upper surface venation] {relief}

Receptacle: 1) The more or less enlarged end of an individual flower stalk (pedicel) which bears some or all of the flower parts. 2) The enlarged end of a compound flower stalk (peduncle) bearing two or more flowers, or the florets of a head, as in the family Asteraceae.

Reflexed: [Leaves, Petals, Sepals] {vertical orientation} Bent backward or downward.

Reniform: [Leaflets, Leaves] {shape} Broader than long, broadly rounded and notched at the base; kidney-shaped.

Resupinate: inverted in position : appearing by a twist of the axis to be upside down or reversed

Reticulate: [Leaf venation, Leaflet venation] {form} With a clearly visible network of interconnecting veins.

Revolute: [Leaf margins, Leaflet margins] {vertical disposition} With margins rolled backward, toward the underside.

Rhizome: [Stems] {type} An underground, usually horizontal stem, often resembling a root but bearing nodes (points where leaves and/or branches can arise); usually with adventitious roots.

Rhombic: [Leaflets, Leaves, Petals, Phyllaries, Sepals] {shape} Broadest at the middle, with more or less straight sides of equal length tapering to either end; diamond-shape.

Ridged: [Bark of mature trunks] {surface appearance} Bark with long, narrow protrusions or ridges, as in tulip-tree (Liriodendron tulipifera).

Root: The portions of a plant that are anatomically distinct from the shoot and that lack nodes and internodes; roots serve for anchorage, absorption and/or storage, and usually grow below ground.

Rosetted: [Leaves] {habit} With leaves in a tight cluster radiating from a central axis, usually at or near the base of the stem, as in dandelion (Taraxacum).

Rounded: [Leaf apices, Leaf bases, Leaflet apices, Leaflet bases, Petal apices, Phyllary apices, Sepal apices] {shape} Forming a smooth, continuous curve.

Rugose: Wrinkled.

Runcinate: [Leaflets, Leaves] {shape} Broad near the apex and tapering toward the base, with a series of coarse, sharp lobes on either side that mostly point toward the base, as a dandelion (Taraxacum) leaf.

Rust: or rust disease : any of numerous destructive diseases of plants produced by fungi of the order Uredinales and characterized by reddish brown pustular lesions on stems, leaves, or other plant parts

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S

Saccate: having the form of a sac or pouch

Sagittate: [Leaf bases, Leaflet bases, Leaflets, Leaves] {shape} Arrowhead-shaped, with the basal lobes directed downward.

Samara: [Fruits] {type} A winged, more or less dry fruit that does not split open at maturity (indehiscent), and contains a single seed, as in ash (Fraxinus) and maple (Acer).

Sap: The fluids circulated throughout a plant.

Saprophytic: [Plants] {nutrition} Obtaining nourishment from dead organic matter.

Scabrous: Rough and sand-papery to the touch, due to structure of the epidermis or to the presence of short stiff hairs.

Scale: 1) Small, flattened structures that are usually thin, dry and membranous in texture. 2) Small, often triangular shaped, leaves that are appressed to the branchlets as in Juniper (Juniperus).

Scale-like: (1) [Leaves] {general form} With small, typically triangular-shaped leaves that are often appressed to the branchlets, as in juniper (Juniperus).

Scale-like: (2) [Petals, Phyllaries, Sepals] {shape} Having the form of small, often triangular shaped, leaves that are appressed to the branchlets, as in juniper (Juniperus).

Scale-like (3) : [Stipules] {type} In the form of a small, flattened structure, usually thin, dry and membranous in texture.

Scaly: [2-4-year-old twigs, Petioles, Rachises] {special surface features} Bearing scales of one kind or another.

Scarious: [Stipules] {type}

Schizocarp: [Fruits] {type} A dry fruit with two or more interior chambers (locules), splitting open (dehiscing) along the partitions between chambers and separating into indehiscent, usually one-seeded segments (mericarps), as in the carrot family (Apiaceae) and Acer.

Scorpioid cyme: [Inflorescences] {type} A cyme in which the lateral branches develop on only one side, each successive segment branching on the side opposite the previous one, producing a more or less zig-zag effect.

Scurfy: Covered with small, bran-like scales.

Secondary vein: A vein in a leaf or other laminar structure that branches from a main or primary vein; a side vein.

Sedges: Members of the Cyperaceae (Sedge family) are collectively known as 'sedges,' although some groups of plants in this family have other common names. The term 'sedge' is used to describe Carex spp. in particular

Seed: A mature or ripened ovule.

Seed Capsule: This consists of the exterior wall and inner cells (if any) of the ovulum (the base of a pistil) after they have become dried out. The seed capsule contains one or more mature or nearly mature seeds. The seed capsule is often ovoid in shape and more or less open at the top, although there are many variations in form

Seed coat: the outer protective covering of a seed that is developed from one or more integuments often in combination with other adherent parts of the ovary (as in a caryopsis)

Seed cone: A female or ovule-producing cone; typically larger and persisting longer than pollen cones.

Seedpod: This is a more or less spongy fruit that contains one or more seeds, often in rows; it often splits apart along one or two sides to release the seeds. Seedpods have variable shapes; in the Brassicaceae (Mustard family), they are often long and cylindrical, while in the Fabaceae (Bean family), they are often flattened and oblong.

Semicircular: [Leaf cross section] {shape} Shaped like a half circle in cross section.

Semi-evergreen: [Leaves] {duration} Bearing green leaves into or through the winter, but dropping them by the beginning of the next growing season; tardily deciduous or winter deciduous.

Semi-persistent: [Seed cones] {persistence} With some cones remaining on the branch after shedding seeds.

Sepal: A unit or segment of the outermost floral envelope or calyx of a flower; usually green and leaf-like.

Sepaloid: resembling or having the nature of a sepal

Septate: This describes leaf blades with cross-sectional venation that span adjacent parallel veins. Some Scirpus spp. (Bulrushes) have septate leaves with cross-sectional venation

Septicidal: dehiscent longitudinally at or along a septum

Septicidal capsule: [Fruits] {type} A capsule that splits open (dehisces) lengthwise along lines formed by the septa or the partitions separating chambers (locules) inside the ovary.

Septifragal: breaking from the partitions -- used of dehiscence in which the valves of a capsule or pod break away from the dissepiments

Septum (plural septa) : A distinct wall or partition that separates the chambers or locules of an ovary, fruit or other structure.

Sericeous: [Buds, Leaf lower surface, Leaf upper surface, Phyllaries, Sepals, Young twigs] {pubescence type} With long, silky, usually appressed hairs.

Serotinous: [Seed cones] {serotiny} Having cones that remain closed long after the seeds are ripe.

Serotiny: The tendency of some seed cones to remain closed long after the seeds are ripe.

Serrate: [Leaf margins, Leaflet margins, Petal margins, Phyllary margins, Sepal margins] {form} Toothed along the margin, the sharp teeth pointing forward; sawtoothed.

Serrulate: [Leaf margins, Leaflet margins] {form} Toothed along the margin with very small, sharp, forward-pointing teeth; finely serrate or small-sawtoothed.

Sessile: [Flowers, Leaflets, Leaves, Seed cones] {form of attachment} Without a stalk, positioned directly against the bearing structure.

Seta: the slender stalk of the sporogonium of a bryophyte e : one of the stalked glands on plants of the genus Rubus f : the bristle in the utricle of some plants of the genus Carex

Shallowly lobed: [Leaflets, Leaves, Petals, Sepals] {lobing} With lobes that are cut approximately  to < the distance to the midrib or base.

Sheath: (1) : the lower part of a leaf (as of a grass) that more or less completely surrounds the stem (2) : an ensheathing spathe (3) ocrea

Sheathing: [Leaf bases, Leaflet bases] {shape} Having a tubular structure partially or completely enclosing the stem below the apparent point of attachment of the leaf blade or stalk (petiole).

Shoot: 1) The portions of a plant that are anatomically distinct from the root and differentiated into nodes, where leaves and branches originate, and the spaces in between (internodes); shoots consist of stems, leaves and any other structures borne from the stem.

Short shoot: A stumpy, slow growing, lateral branch with very short internodes, often bearing flowers; a dwarf shoot.

Shreddy: [Bark of mature trunks] {surface appearance} Soft but coarse, fibrous bark, usually shallowly furrowed, as in eastern red cedar (Juniperus virginiana).

Shrub: [Plants] {habit} A relatively short, woody, perennial plant, usually without a single stem or trunk, and often with many crowded branches.

Silicle: [Fruits] {type} A dry fruit that splits open (dehisces) along two sutures, the exterior walls eventually falling away in two halves, leaving a single, persistent, interior partition (septum) to which the seeds are attached; usually not more than twice as long as wide; common in the mustard family (Brassicaceae).

Silique: [Fruits] {type} A dry fruit that splits open (dehisces) along two sutures, the exterior walls eventually falling away in two halves, leaving a single, persistent, interior partition (septum) to which the seeds are attached; usually at least twice as long as wide; common in the mustard family (Brassicaceae).

Simple: [Leaves] {complexity} Undivided, as a leaf blade that is not separated into distinct leaflets; not compound. [modified from H&H, p. 156]

Simple dichasium: [Inflorescences] {type} A determinate, cymose, three-flowered inflorescence composed of a main stalk bearing a terminal flower and a pair of opposite or nearly opposite lateral flowers.

Simple ovary: An ovary composed of only one carpel; recognizable by the presence of only one area of placentation, locule, ovary lobe, style (or style branch), and stigma.

Simple umbel: [Inflorescences] {type} An inflorescence composed of several branches that radiate from almost the same point, like the ribs of an umbrella, each terminated by one or more flowers, the upper surface of the whole inflorescence rounded, or more or less flat.

Single scale: [Bud scales] {type} Covered by a single scale.

Sinuate: [Leaf margins, Leaflet margins, Petal margins, Phyllary margins, Sepal margins] {form} With the margin smoothly and shallowly indented; wavy in a horizontal plane.

Sinus: The space or recess between two divisions or lobes of an organ such as a leaf or petal.

Smooth: (1) [Buds, Young twigs, Leaves] With an even surface; not rough to the touch.

Smooth: (2) [Bark of mature trunks] {surface appearance} Bark having a more or less continuous, even surface, with relatively few fissures or protrusions, as in (Fagus grandifolia).

Smooth (3) : [Apophyses] {texture} With an even surface, lacking keels, grooves or other surface features.

Solitary: [Inflorescences] {type}; [Needles] {presence of clusters or fascicles } Occurring singly and not borne in a cluster or group.

Sorus (pl. sori) : a cluster of reproductive bodies or spores on a lower plant : as a : a clump of sporangia on a fertile frond of a fern

Spadix: [Inflorescences] {type} An inflorescence with small, stalkless (sessile) flowers more or less embedded in a thick, fleshy, unbranched axis or rachis, the whole inflorescence subtended and sometimes partially enclosed by a specialized bract or spathe, as in Jack-in-the-pulpit (Arisaema triphyllum).

Spathe: An often large, sometimes colored and flowerlike bract subtending and sometimes partially enclosing an inflorescence, as in calla lily (Zantedeschia) or jack-in-the-pulpit (Arisaema triphyllum).

Spatulate: [Leaflets, Leaves, Petals, Phyllaries, Sepals] {shape} Broad and rounded near the apex with a narrower, long, tapering base; spatula-shaped or spoon-shaped.

Spike: [Inflorescences] {type} A usually indeterminate, elongate inflorescence with unstalked (sessile) flowers arranged singly along an unbranched axis or rachis.

Spikelet: [Inflorescences] {type} The basic unit of inflorescence in the sedges (Cyperaceae) and grasses (Poaceae) consisting of a spike of tiny flowers that lack petals, each subtended by scale-like bracts; spikelets are the ultimate subdivision in a typically more complex inflorescence.

Spine: A woody, sharp-pointed, modified leaf or leaf part.

Spinose: (1) [Leaf apices, Leaflet apices, Petal apices, Phyllary apices, Sepal apices] {shape} Ending in a rigid, tapering, sharp tip; bearing a spine at the apex.

Spinose: (2) [Stipules] {type} Modified into a woody, sharp-pointed structure, as a stipular spine.

Spiny or prickly: [Leaf margins, Leaflet margins, Phyllary margins, Sepal margins] {form} Bearing spines or prickles along the margin.

Spiny, prickly, thorny: [2-4-year-old twigs, Petioles, Rachises] {special surface features} Bearing spines, prickles or thorns.

Spiral: [Leaves] {insertion} Arranged along the stem in such a way that a line connecting the points of attachment would form a spiral; a form of alternate arrangement.

Sporangium: (pl. sporangia) A spore-bearing case or sac.

Spores: Spores are produced by ferns, horsetails, and other primitive plants. Spores resemble tiny seeds, but they lack food for the plant embryo. Because spores are easily carried aloft by the wind, they allow ferns and horsetails to reproduce asexually across considerable distances. However, some species of plants, e.g. Isoetes spp. (Quillworts), reproduce sexually by producing both male and female spores. Because the female spores are larger in size than the male spores, they are referred to as 'macrospores.'

Spotted [Leaf lower surface, Leaf upper surface] {color variegation} The color disposed in small spots.

Spreading: [Leaves, Petals, Phyllaries, Sepals] {vertical orientation} Extending outward horizontally, or upward at an angle between 90: to 45: relative to the bearing structure.

Spurred: [Petals] {shape}

Squarrose: [Phyllaries] {vertical orientation}

Stalk: A supporting axis or column that bears a structure at its apex and is usually narrower than the structure being borne, as the stalk of a flower or leaf.

Stalked: [Flowers, Seed cones] {form of attachment} With a stalk.

Stamen: The male reproductive organ in a flower that produces and releases pollen, composed of an anther usually borne on a stalk (filament).

Staminate: [Flowers] {gender} Having one or more functional stamens, but no functional pistils, making the flower unisexual and male.

Staminodium: an abortive or sterile stamen (as in the flowers of the genus Parnassia)

Stellate: [Buds, Leaf lower surface, Leaf upper surface, Petioles, Phyllaries, Rachises, Sepals, Young twigs] {pubescence type} With hairs that branch from the base and resemble tiny stars.

Stem: The axis of a shoot, bearing leaves, bracts and/or flowers, and usually growing above ground, but sometimes specialized and growing underground (see bulb, corm, rhizome and tuber) or on the surface of the ground (see stolon); stems are differentiated into regions called nodes, where leaves and branches originate, and internodes.

Sterigma-bearing: [2-4-year-old twigs] {special surface features} With persistent leaf bases that remain on the twig after the leaf falls and appear as peg-like projections.

Stigma: The pollen-receptive region at the tip of a pistil.

Stinging: [Leaf lower surface, Leaf upper surface, Petioles, Phyllaries, Rachises, Sepals, Young twigs] {pubescence type} With erect, usually long hairs, that produce irritation when touched, as in stinging nettle (Urtica).

Stipitate glandular: [Buds, Leaf lower surface, Leaf upper surface, Petioles, Phyllaries, Rachises, Sepals, Young twigs] {pubescence type} With stalked glandular hairs.

Stipule: A relatively small, typically leaf-like structure occurring at the base of a leaf stalk (petiole), usually one of a pair; stipules are sometimes in the form of spines, scales or glands.

Stipule scar: The scar remaining on a twig at the former place of attachment of a stipule.

Stolon: [Stems] {type} A slender horizontal stem, at or just above the surface of the ground, that gives rise to a new plant at its tip or from axillary branches.

Stoloniferous: A stoloniferous root system has above ground runners (stolons) that can produce new plantlets some distance away from the mother plant.

Strigose: [Buds, Leaf lower surface, Leaf upper surface, Phyllaries, Sepals, Young twigs] {pubescence type} With straight, stiff, sharp appressed hairs.

Striped [Leaf lower surface, Leaf upper surface] {color variegation} Longitudinal, or ertical, stripes of one color crossing another.

Strobilus: a conelike aggregation of sporophylls (as in the club mosses and horsetails) b : the cone of a gymnosperm

Strong: [Seed cone armature] {strength} With sturdy armature that is not easily broken.

Style: The more or less elongated portion of a pistil between the ovary and the stigma.

Subshrub: [Plants] {habit} 1) A shrub-like plant but with only the base composed of woody tissue, the herbaceous branches dying back at the end of each growing season 2) A very low shrub that sprawls on the ground; a trailing shrub.

Subtend: to occupy an adjacent and usu. lower position to and often so as to embrace or enclose (a bract ~ing a flower)

Succulent: [Plants] {habit} Juicy, fleshy and often thickened, as the stem of a cactus or the leaves of Aloe.

Superior: [Ovaries] {position} With the ovary not fused to any portion of a floral cup, the whorl of sepals and petals (perianth) and/or stamens (androecium) thus arising from beneath the ovary. (Compare with inferior and half-inferior.)

Superposed: [Buds] {position} Located directly above an axillary bud.

Swollen: protuberant or abnormally distended: Swollen node

Syconium: [Fruits] {type} A multiple fruit characteristic of the figs (Ficus) with an enlarged, hollow, flask-like structure that becomes fleshy at maturity and bears numerous tiny, dry fruits along the inner surface.

Symmetric: [Seed cones] {symmetry} Divisible into essentially equal halves along one or more planes.

Sympetalous: [Corolla] {fusion} With petals united, at least at the base.

Synoecious: [Plants] {distribution of gender} With all flowers or cones bisexual, i.e. bearing functional reproductive structures of both sexes. (Compare with dioecious and monoecious.)

Synsepalous: [Calyx] {fusion} With sepals united, at least at the base.

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