A

Abaxial:

(Dorsal) The side or face away from the axis. Most commonly used here when referring to the lower margin of the phyllode. See Adaxial.

Acicular:

Needle-shaped.

Acuminate:

Tapering gradually to a protracted point. See Caudate .

Acute:

Tapering to a distinct but not protracted point, with more or less straight sides forming an angle of less than 90 degrees.

Adaxial:

(Ventral) The side or face next to the axis. Most commonly used here when referring to the upper (gland-bearing) margin of the phyllode. Compare Abaxial .

Anastomosing:

Nerves branching and rejoining to form an intertwining network. See Nerve islands and Reticulum .

Anther:

The pollen-bearing part of the stamen.

Anthesis:

The flowering period, when flowers are fully expanded and functioning. Acacia flowers are considered to be at anthesis when the anthers are exserted.

Antrorse:

Directed forward or upward. Most commonly used here with for hairs that are bent towards the apex of branchlets or phyllodes. Compare Retrorse.

Aphyllous:

Without leaves or phyllodes.

Apiculate:

Tipped by a short, slender, flexible and often sharp point.

Appressed:

Pressed close or flat against another organ.

Arachnoid:

Bearing long, cobwebby, entangled hairs.

Arborescent:

Treelike.

Arcuate:

Curved into an arch, like a bow.

Areole:

A small, well-defined area on a surface. Used here mainly to describe the area on the seed surface circumscribed by the pleurogram.

Aril:

The expanded end of the funicle. Commonly there is a morphological discontinuity between the funicle and the aril, however, sometimes there is no clear distinction between the two and then the whole structure is referred to as the funicle/aril . See Exarillate and Funicle .

Aristate:

Bearing an awn or bristle at the tip.

Article:

As used here the term applies to the one-seeded segments of a pod which are separated from one another by deep constrictions of the pod valves.

Articulate:

Jointed; having joints where separation may occur naturally.

Ascending:

Growing upwards, with an angle of divergence of 16-45 degrees.

Asymmetric:

Not symmetric.

Attenuate:

Tapering gradually to a narrow tip or base.

Axes:

Plural from axis

Axil:

The point of the upper angle formed between the branch and the phyllode.

Axillary:

(inflorescences) Arising within the angle (axil) formed by the branchlet and the phyllode. See Simple .

Axillary spine:

(= Thorn ) A rigid, woody modified stem with a +/- sharp point; unlike prickles axillary spines have a vascular trace.

Axis:

(pl. axes) The central supporting structure (or imaginary line) around which various organs are developed, for example, peduncles borne on a raceme axis.

B

Bifarious:

In two vertical rows.

Bifid:

Deeply two-cleft or two-lobed, usually from the tip.

Bifurcate:

Two-forked.

Binate:

Borne in pairs.

Bipinnate:

Twice pinnate, i.e. compound leaves comprising a central axis and (one to many) secondary axes arranged on opposite sides of it (leaflets are arranged on opposite sides of the secondary axes).

Bloom:

A whitish, powdery or waxy coating on a surface. See Pruinose .

Bole:

The trunk of a tree.

Brachyblast:

A short branch.

Bract:

A reduced leaf or leaf-like structure associated with a flower or inflorescence.

Bracteole:

Small bract that subtends each flower.

Branch:

Primary divisions of the stem.

Branchlet:

Ultimate divisions of the branch.

C

Caducous:

Falling off early. Compare Deciduous.

Callous:

Hardened or thickened; having a callus.

Callus:

A hard thickening or protuberance.

Calyx:

A collective term for all the sepals of a flower.

Canescent:

Grey or white in colour due to a covering of short, fine hairs.

Capitate:

Head-like, or in a head-shaped cluster.

Capitulum:

A small cluster of sessile flowers.

Carpological:

Pertaining to fruits.

Cartilaginous:

Tough and firm but elastic and flexible, like cartilage.

Castaneous:

Chestnut-coloured; dark reddish brown.

Caudate:

Excessively acuminate, so that the point is long and weak, like the tail of some animals.

Chartaceous:

With a papery texture.

Ciliate:

With a marginal fringe of hairs. Dim. Ciliolate.

Cinereous:

Ash-coloured.

Circinnate:

Used here to describe pods where they are curved or coiled within the plane of the suture (if curving normal to suture the term coiled is used).

Clavate:

Club-shaped.

Coiled:

To wind into rings, one above another, with the opposite ends overlapping. The coils can be regular or irregularly formed, and may form a tight spiral. As used here this term is most commonly applied to pods with coils normal to the plane of the suture. See Circinnate.

Compound leaf:

A leaf divided into two or more leaflets. See Bipinnate and Pinnate.

Compressed:

As used here the term is applied to narrow, “thick” organs, especially phyllodes, which are subjectively judged as being intermediate between Flat and Sub-terete .

Concolorous:

Of one colour. Use here for when the upper and lower surfaces of leaflets are uniform in colour and shade of colour.

Confluent:

Blending of one part into another. Used here with reference to phyllode nerves. Different from Contiguous .

Connate:

Fusion of like parts, as the fusion of staminal filaments into a tube.

Contiguous:

Adjoining or touching (but not blending). Different from Confluent .

Continuous:

Not jointed; not separating at maturity along a well-defined line of dehiscence. See Decurrent .

Convex:

Rounded and curved outwards on the surface.

Coppice:

New growth arising from a stump.

Cordate:

Heart-shaped, with a notch at the base.

Coriaceous:

With a leathery texture.

Crenate:

With rounded teeth along the margin.

Crenulate:

With very small rounded teeth along the margin.

Crisped:

Curled, wavy or crinkled. Used here with reference to hairs of the indumentum.

Crowded:

When similar parts are close together, as in phyllodes along branchlets or longitudinal nerves on plurinerved phyllodes.

Crustaceous:

With a hard, brittle texture.

Cucullate:

Hooded or hood-shaped.

Cultrate:

Having the shape of a knife-blade.

Cuneate:

Having three sides and three angles, with the widest axis above the middle; length: width ratio >2: 1 to <12: 1. A 2-dimensional shape. See Obdeltate and Obtriangular .

Cupular:

Cup-shaped; nearly hemispherical, like an acorn-cup.

Curved:

When an organ is continuously bent into an arc (but the ends not overlapping.

Cusp:

A short, sharp point.

Cuspidate:

Tipped with a short, sharp point.

Cuticle:

The waxy layer on the surface of a leaf or branch.

Cylindrical:

Cylinder-shaped; elongate (more than twice as long as wide) and round in cross-section. See also Spike .

D

Deciduous:

Falling off; not persistent. Compare Caducous.

Decumbent:

Spreading horizontally (of the reclining on the ground) but with the tips growing upwards.

Decurrent:

Extending downward from the point of insertion, e.g. base of phyllodes that extend down along the branch as a wing (broad or narrow) or rib.

Deflexed:

Bent abruptly downward.

Dehiscence:

The opening at maturity of pods.

Deltate:

Having three sides and three angles, with the widest axis below the middle; length: width ratio about 1: 1. A 2-dimensional shape. See Triangular.

Dense:

(heads or spikes) Flowers pressed closely together. Compare interrupted.

Depressed:

Sunk down, as if flattened from above.

Diaphyllode:

Phyllode flattened in the horizontal plane (as opposed to being flattened in the vertical plane, which is what normally occurs in Acacia). In diaphyllodes the gland is found on the upper surface of the lamina, not on the upper edge as occurs in vertically flattened phyllodes.

Diffuse:

Widely or loosely spreading.

Dimidiate:

Halved.

Dimorphic:

With two forms.

Disciform:

In the form of a disk.

Discoid:

Resembling a disk.

Discolorous:

Of different colours. Use here for when the upper and lower surfaces of leaflets are unlike in colour (commonly different shades of green).

Distal:

Towards the tip, or the end of the organ opposite the end of attachment. Compare Proximal .

Distant:

When similar parts are not closely aggregated, as in longitudinal nerves of plurinerved phyllodes that are widely spaced.

Distichous:

Arranged in two ranks or rows on opposite sides of an axis (e.g. stem) and thus in the same plane.

Divaricate:

Widely diverging or spreading apart.

Dorsal:

See Abaxial .

Dorsiventral:

Having structurally different upper and lower surfaces.

Downy:

Covered with soft, fine hairs.

E

Ebracteate:

Without a bract.

Echinulate:

With small prickles or spines.

Edaphic:

Pertaining to soil.

Eglandular:

Without a gland.

Ellipsoid:

A solid body elliptic in long section.

Elliptic:

In the shape of an oval, i.e. broadest at middle with curved sides. Length to width ratio about 2: 1. A 2-dimensional shape. See Narrowly elliptic .

Emarginate:

With a notch at the apex.

Endemic:

Peculiar to a specific geographic area.

Epidermis:

The true cellular skin or covering of a plant organ situated below the cuticle.

Erect:

Growing upwards, with an angle of divergence of less than 16 degrees.

Erose:

The margin irregularly toothed, as if gnawed.

Exarillate:

Without an aril.

Excentric:

Off-center.

Exserted:

Projecting beyond the surrounding parts, as bracteoles protruding beyond flower buds.

Extra-floral:

(nectary) See Gland.

F

Falcate:

Sickle-shaped or scimitar-shaped. See Sub-falcate.

Fasciculate:

Clustered from a common point.

Ferruginous:

Rust-coloured.

Fibrous:

Containing or resembling fibre.

Filiform:

Thread-like.

Fimbriolate:

Fringed with minute hairs along the margin.

Flaccid:

Limp, not rigid.

Fleshy:

Thick and pulpy; succulent.

Flexuose:

Zig-zagged.

Fluted:

With furrows or grooves.

Foliaceous:

Leaf-like; bearing leaves.

Friable:

Crumbly.

Fuligineus:

Sooty, or soot-coloured.

Funicle:

The cord that connects the seed to the pod (or the ovule to the placenta). See Aril.

Fusiform:

Spindle-shaped; broadest near the middle and tapered towards both ends.

G

Galeiform:

Helmet-shaped.

Gamopetalous:

Having the pepals united by their margins, at least at the base.

Gamosepalous:

Having the sepals united by their margins, at least at the base.

Geminate:

In equal pairs like twins.

Gibbose:

(Gibbous) Swollen or enlarged on one side; a pouch-like enlargement of the base of an organ.

Glabrescent:

Becoming glabrous, especially with age or maturity (i.e. defines the process).

Glabrous:

Without hairs.

Gland:

Small secretory structures (extra-floral nectaries) normally situated on the leaf. See also Jugary gland , Interjugary gland and Petiolar gland .

Glaucous:

Blue-green colour (normally with a surface bloom). See Pruinose.

Globose:

(globular) Spherical.

Glutinous:

Sticky. Same as Viscid .

H

Habitat:

The environmental circumstances or kind of place where an organism occurs.

Head:

A spherical or obloid aggregation of flowers. When the flower cluster is elongated (cylindrical, i.e. more than twice as long as wide) it is called a spike .

Heads:

Plural from head.

Herbaceous:

A vascular plant that never produces a woody stem.

Hexagonal:

Six-angled.

Hilar:

Relating to the hilum.

Hilum:

The scar left on the seed where the funicle was attached.

Hirsute:

Hearing coarse, long hairs.

Hirtellous:

Minutely hirsute. Used here to describe an indumentum comprising short, straight, fine, spreading hairs.

Hispid:

Having long, erect, rigid hairs or bristles, harsh to the touch.

Hispidulous:

Minutely hispid.

Hoary:

Grey or white from a fine layer of hairs.

Hyaline:

Translucent, almost like clear glass.

I

Imbricate:

Overlapping like tiles or shingles on a roof.

Impressed:

Situated below the surface, as in some phyllode nerves.

Inaequilateral:

Unequal sided.

Inclined:

Ascending with an angle of divergence of 46-75 degree.

Incurved:

Curved upwards or inwards. See also Curved and Recurved.

Indehiscent:

Not opening at maturity along definite lines or pores.

Indumentum:

A covering of hairs.

Indurate:

Hardened.

Inflorescence:

The arrangement of the flowers and flowering axes. In acacia the flowers are aggregated into globular or obloid heads or cylindrical spikes, these are borne on peduncles (peduncles rarely absent) which may simple or arranged in racemes or panicles.

Innocuous:

Harmless; without a sharp point.

Interjugary glands:

Glands situated on upper surface of the rachis between successive pairs of pinnae, but located more than 1 mm below the insertion of the pinnae. One to several interjugary glands may be present; they may vary in size but are generally smaller than the jugary glands (which may co-occur on the same leaf).

Internode:

The portion of a branchlet between adjacent nodes.

Interrupted:

(as to spikes) Individual flowers widely spaced so that the inflorescence axis (i.e. the receptacle) is clearly visible between at least the unopened flowers. Compare Dense .

Interstices:

A space between. Used here mainly with reference to the space between adjacent longitudinal nerves of plurinerved phyllodes.

Involucre:

A ring of bracts subtending a flower or flower cluster. In a cacia involucres are found only in members of Vachellia. The involucre may occur anywhere along the peduncle, from the base to the apex; in the latter case it may be hidden by the flowers when heads or spikes are at anthesis.

Iridescent:

Displaying many colours.

J

Jugary glands:

Glands situated on upper surface of the rachis of a multi-jugate leaf between, or up to 1 mm below, the base of a pair of pinnae (excluding the lowermost pair). Inter-jugary may co-occur on leaves with jugary glands. See also Glands.

L

Laciniate:

Cut into narrow, irregular lobes or segments, as occurs in the calyx of a few species.

Lamina:

The expanded portion, or blade, of a leaf or petal, etc. In acacia this term is applied to the expanded apex found on many bracteoles and sometimes to the body of the phyllodes (excluding the pulvinus).

Lanate:

Wooly; densely covered with long, soft tangled hairs.

Lanceolate:

Lance-shaped. A term of varied application but as used here refers to a shape that is longer than wide with the broadest point below the middle, and with +/- curved sides. Length to width ratio more than 3: 1 A 2-dimensional shape. If length: width ratio is less than 3 then see Ovate.

Lateral:

Borne on or at the side.

Leaf axis:

The main axis of a compound leaf. In bipinnate-leaved species the leaf axis comprises the petiole and (if present) the rachis; it is terminated by the terminal seta.

Leaflet:

(syn. pinnule ) The ultimate division of a compound leaf.

Legume:

See pod.

Lenticel:

Somewhat corky spots on the bark (these are small, pale-coloured and can be circular, lens-shaped or slit-like).

Lenticellular:

Invested with lenticels.

Liane:

Woody, climbing vine.

Linear:

Resembling a line, i.e. long and narrow (more than about 9 times longer than wide) with parallel sides. A 2-dimensional shape. If length: width ratio is less than 9 then see Narrowly oblong or Oblong .

Linear-oblanceolate:

Like oblanceolate but very long and narrow.

Linear-triangular:

Triangular but with length: width ratio 12: 1 or more. A 2-dimensional shape.

Longitudinal:

Parallel to the long axis of a structure, e.g. nerves of a phyllode, seeds in a pod.

M

Mealy:

Farinaceous; powdery, dry and crumbly.

Membranous:

Thin, soft, flexible, and more or less translucent, like a membrane.

Merous:

The number of parts within a set. Here used with reference to flowers, for example, 5-merous flowers have 5 petals and 5 sepals.

Midrib:

The central longitudinal nerve of the phyllode or petal.

Moniliform:

Cylindrical and constricted at regular intervals, giving a beaded necklace-like appearance, e.g. pods of A. coriacea. See Sub-moniliform .

Mottled:

With coloured spots or blotches.

Mucro:

A small point (usually brown, hard and sometimes sharp), found at tips of leaflet.

Mucronate:

Tipped with a mucro.

Mucronulate:

Tipped with a very small mucro.

Multi-jugate:

Leaves possessing more than one pair of pinnae.

Multi-stemmed:

With 4 or more trunks or stems arising from ground level.

Multi-striate:

(phyllodes) Possessing many, fine, close, parallel nerves.

Muricate:

Rough on the surface due to minute, hard outgrowths of the epidermis.

N

Narrowly elliptic:

Elliptic but with length to width ratio 3: 1 or more.

Narrowly oblong:

Oblong but with length to width ratio 3: 1 to 9: 1.

Naturalized:

Plants introduced from elsewhere, but now established.

Navicular:

Boat-shaped.

Nervation:

The arrangement of nerves or veins in an organ, as in phyllodes.

Nerve:

A strand of vascular tissue.

Nerve islands:

Enclosed spaces created by anastomosing nerves that form the reticulum. See Anastomosing and Reticulum.

Nitid:

Shiny.

Node:

The position on the stem where leaves or branches originate.

Nodose:

With knobs.

O

Obconic:

Cone-shape, with the attachment at the narrower end.

Obdeltate:

Having three sides and three angles, with the widest axis above the middle; length: width ratio about 1: 1. A 2-dimensional shape. See Cuneate and Obtriangular.

Oblanceolate:

Inversely lanceolate, with the attachment at the narrower end. A 2-dimensional shape.

Oblate:

Spheroidal and flattened at the poles.

Oblique:

Slanting.

Obloid:

(syn. Oblongoid) A short cylinder (not above twice as long as wide). Used here with reference to the shape of flower-heads. See Heads.

Oblong:

Rectangular (length to width ratio >1: 1 to <3: 1), with parallel sides. A 2-dimensional shape. If length: width ratio is 3 or more than see Linear or Narrowly oblong.

Obovate:

Inversely ovate, with the attachment at the narrower end (not as elongate as oblanceolate). Length: width ratio about 2. A 2-dimensional shape. See Oblanceolate.

Obtriangular:

Inversely triangular. Having three sides and three angles, with the widest axis above the middle; length: width ratio about 2: 1. A 2-dimensional shape. See Cuneate and Obdeltate.

Obtuse:

Rounded at apex with the sides coming together at an angle greater than 90 degrees. See Rounded.

Opposite:

Two phyllodes or other structure per node, positioned on opposite sides of the branch or central axis.

Orbicular:

Circular. Length to width ratio 1: 1.

Orifice:

(of glands) The opening, or pore, usually located in the centre of extra-floral nectaries (glands).

Ovary:

The swollen basal portion of the female reproductive organ with contains the ovules. Acacia flowers typically have a single ovary (rarely more) and this is terminated by the style (which often protrudes just beyond the stamens when flowers are at anthesis).

Ovate:

Egg-shaped in outline and attached at the broad end. Length: width ratio about 2. A 2-dimensional shape. If length: width ration is more than 3 then see Lanceolate.

Ovule:

An immature seed; the megasporangium and surrounding integuments of a seed plant.

P

Panicle:

A branched, racemose inflorescence (i.e. a raceme of racemes).

Papilla:

(pl. Papillae) Small, elongated protuberances on the surface of an organ, usually an extension of one epidermal cell.

Papillae:

Plural from papilla

Papillose:

Having minute papillae.

Patent:

Widely spreading (at about a right angle to the supporting axis).

Peduncle:

The stalk of an inflorescence terminated by a head or a spike.

Peduncular bracts:

See Basal peduncular bracts and Involucre.

Peltate:

Target-shaped; a flat structure borne on a stalk which is attached to the lower surface rather than to the base or margin.

Pendulous:

(Pendent) Hanging or drooping downwards.

Penninerved:

Nerves parallel to one another and arising from a main central axis as in minor nerves of phyllode diverging from midrib.

Pentagonal:

Five-angled.

Pentamerous:

With parts arranged in sets or multiples of five, as in flowers having 5 sepals.

Persistent:

Remaining attached to the plant beyond the expected time of falling.

Petiolar gland:

Glands located on the upper surface of the petiole, between or below the point of insertion of the pinnae. Petiolar glands can be sessile or stipitate.

Petiole:

A leaf stalk. In bipinnate-leaved acacias the petiole is the leaf stalk lying between the branchlet and the point of attachment of the first pair of pinnae; the base of the petiole is occupied by the pulvinus.

Petiolule:

The stalk of a leaflet.

Phenology:

Abbreviated from phenomenology, recording the periodical phenomena of plants. As used here the term applies to the appearance of flowers and fruits.

Phyllode:

A modified primary leaf axis which assumes the form and function of a leaf.

Pileate:

Having the form of a cap.

Pilose:

Covered with usually long and spreading, soft, weak, thin and clearly separated hairs.

Pinna:

(plural: pinnae) In bipinnate-leaved acacias the pinna represents one of the primary divisions of the leaf (they comprise the rachilla together with the leaflets it supports). Pinna are inserted on the petiole and (when present) the rachis, occurring as an opposite pair of pinnae, however, sometimes they are sub-opposite or alternate.

Pinnae:

Plural from pinna

Pinnate:

A compound leaf with leaflets arranged on opposite sides of a central main axis.

Pinnule:

See Leaflet.

Plane:

With a flat surface.

Plano-convex:

Flat on one side and convex on the other.

Pleurogram:

The fine line that circumscribes the areole that occurs on the opposite faces of the seeds. The pleurogram can be open (the opening always faces the hilum) or closed (in which case it is termed "continuous"); when open the pleurogram is commonly "u" shaped.

Plicate:

Folded back and forth longitudinally like a fan.

Pod:

(Legume) A usually dry, dehiscent fruit derived from one carpel that splits along two sutures.

Prickle:

Short, sharp-pointed, hardened outgrowths of the epidermis, with no vascular tissue connecting them to the branchlet.

Procumbent:

Trailing or spreading along the ground but not rooting at the nodes.

Prostrate:

Lying flat on the ground. See also Sub-shrub.

Proximal:

Towards the base, or the attachment end of the organ. Compare Distal.

Pruinose:

With a white powdery coating (bloom) on the surface. This term is treated by many authors as equivalent to glaucous. See Scurfy.

Puberulous:

Minutely hairy with a somewhat dense cover of very short, soft hairs.

Pubescent:

A somewhat dense cover or short, weak, soft hairs.

Pulvinus:

Classically defined as the swollen base of the petiole.

Punctate:

Marked with dots, depressions or translucent glands.

Puncticulate:

Minutely punctate.

Pungent:

Tipped with a sharp, rigid point.

Pustulate:

With small blisters.

Q

Quadrangular:

Four-cornered; having four angles, which are usually right angles.

R

Raceme:

An inflorescence comprising pedunculate heads or spikes arranged along an unbranched common axis (the raceme axis). More correctly this structure should be termed a raceme of heads or spikes.

Raceme axis:

The primary axis of the raceme.

Raceme bracts:

See Basal raceme bracts.

Rachilla:

Used here to denote the secondary axis of a bipinnate leaf upon which the leaflets are inserted.

Rachis:

The main axis of a structure, such as the a compound leaf or an inflorescence. The rachis is the leaf axis extending from the lowermost to the uppermost pair of pinnae; it is situated distal to the petiole and is terminated by the terminal seta.

Receptacle:

The distal end of the peduncle upon which the flowers are inserted (in fruiting specimens the receptacle is normally marked with scars where flowers have fallen).

Recurved:

Curved downwards or outwards. See also Curved and Incurved. The term recurved is used for leaflets where the margins are curved backwards towards the underside or the leaflet. See also Revolute.

Reflexed:

Bent backward or downward to some degree.

Repand:

With a slightly wavy or weakly sinuate margin; undulate.

Resinous:

Bearing resin. Resin is a term applied to a group of oxydised hydrocarbons, solidified or hardened turpentine, and insoluble in water. Resin may or may not be sticky (i.e. viscid).

Reticulum:

A network formed by anastomosing veins. See Anastomosing and Nerve islands.

Retrorse:

Directed backwards or downwards. Most commonly used here with for hairs that are bent towards the base of branchlets or phyllodes. Compare Antrorse.

Retuse:

With a shallow notch in a rounded or blunt end.

Revolute:

With margins rolled backward towards the underside. See also Recurved.

Rhombic:

Shaped like a rhomb (rhomb: an oblique-angled, equilateral parallelogram).

Rhomboid:

Approaching a rhombic outline. See Trapeziform.

Rib:

A main longitudinal vein in a structure, as in branchlets.

Rigid:

Stiff and inflexible.

Rimose:

With longitudinal fissures or cracks. Used here with reference to bark.

Rostellate:

Having a small, terminal beak.

Rostriform:

Beak-shaped.

Rounded:

Forming a smooth arc, like an arc of a circle. Like Obtuse except arc forming a wider angle.

Rudimentary:

Imperfectly developed (as applied here this term refers to structures, commonly phyllodes or racemes, that are extremely short).

Rugose:

Wrinkled.

S

Scabridulous:

Minutely roughened.

Scabrous:

Rough to the touch with short, hard rigid emergences or hairs.

Scale:

A thin, flat, dry, membranous, non-green (commonly brown) structure.

Scandant:

Climbing.

Scarious:

Thin-textured and dry, not green.

Scattered:

Irregularly arranged.

Scurfy:

Covered with small, bran-like scales. See Pruinose.

Semi-trullate:

Half trowel-shaped. Widest axis below the middle and having a +/- straight lower margin and an angled upper margin. A 2-dimensional shape.

Sepal:

A segment of the calyx. In acacia sepals may be free (in which case they are often difficult to see) or united into a variously lobed cup.

Sericeous:

Silky with soft appressed hairs.

Serpentinous:

See Sinuous.

Sessile:

Sitting upon the body that supports it, without a supporting stalk.

Seta:

(pl. setae) A bristle or stiff hair.

Setae:

Plural from seta

Setose:

Bristly.

Shrub:

Woody plant, single- or multi-stemmed, more than 0.3 m tall and usually less than 3 m tall, erect, spreading or domed. Sometimes it is difficult to distinguish between Shrub, Sub-shrub and Tree.

Sigmoid:

S-shaped; doubly curved, like the letter S. Commonly applied to phyllodes. When the curves are very shallow a subjective distinctions must sometimes be made between Sigmoid and Curved or Straight.

Simple:

(inflorescences) Unbranched. As used here the term refers to peduncles that are axillary (i.e. not inserted on a common axis, as occurs in racemes and panicles).

Sinuous:

(Serpentinous) Curving in and out in a wavy or serpentine form.

Spathulate:

Shaped like a spatula, with a rounded blade above gradually tapering to the base.

Spike:

An elongated (cylindrical) aggregation of flowers along a receptacle at the distal end of the peduncle. See Head.

Spinose:

Hard, rigid and sharp-pointed structures (which readily pierce the skin upon touch); normally applied here to branchlets and stipules. Sometimes it is difficult to decide if the tips are Spinose or Sub-spinose.

Spirally twisted:

are Spinose or Sub-spinose.

Spirally twisted. Twisted in a continuous curve around a central axis.

Squamulose:

With minute squamellae, i.e. small scales. Beset with small scales.

Stamen:

The male reproductive organ of a flower, consisting of an anther and a filament.

Stellate:

Star-shaped, as in hairs with several to many branches radiating from the base.

Stem:

The main axis of a plant.

Sterile:

Infertile. Used here mainly with reference to plants bearing neither flowers nor fruits.

Stipe:

A stalk supporting a structure, such as the stalk attaching an ovary to the receptacle in some flowers.

Stipitate:

Borne on a stipe.

Stipules:

Small appendages located on the branchlets at the base of leaves.

Stomata:

A pore or aperture in the epidermis, surrounded by two guard cells, which allows gaseous exchange.

Straight:

Without a curve, bend or angle.

Striate:

Marked with fine parallel lines, as grooves or ridges.

Strigose:

Covered with appressed, rigid, bristle-like straight hairs.

Strigulose:

Minutely strigose.

Sub-:

A prefix denoting slightly, somewhat, or almost.

Sub-acute:

Intermediate between Acute and Obtuse.

Sub-appressed:

Intermediate between Appressed and Patent (i.e. forming an angle of about 15-75 degrees with the surface).

Sub-distant:

Intermediate between Distant and Crowded.

Sub-falcate:

Shallowly falcate (in sub-falcate phyllodes the upper margin is convex and the lower margin is shallowly concave).

Sub-glabrous:

Hairs very sparse, almost absent.

Sub-nitid:

Sub-shiny.

Sub-shrub:

Dwarf woody plant, single- or multi-stemmed, to 0.3 m tall and erect, spreading or domed (not to be confused with Prostrate).

Sub-spinose:

Tips hard, rigid and often acute (but not piercing the skin upon touch); normally applied here to branchlets, stipules and phyllodes. Sometimes it is difficult to decide if the tips are Sub-spinose or Spinose.

Sub-terete:

Sub-rounded in cross-section (i.e. terete but slightly flattened horizontally or vertically). See Terete and Compressed.

Subulate:

Awl-shaped.

Sub-whorled:

Three or more phyllodes arranged in an incomplete, horizontal or oblique, ring round the stem at the node. This somewhat loosely defined term accommodates phyllode arrangements intermediate between regular whorls and clearly scattered.