Neotropical Flowering Plants

Explanation of characters and character states in the key

Plant type

Dicotyledon or monocotyledon




Woody plant - [Stem hard and lignified in texture; includes some woody-based, herbaceous species]

Non-woody plant - [Stem soft in texture: mostly herbaceous species]


Tree or treelet - [A woody plant with one main trunk or bole and a distinct head]

Shrub or subshrub - [Woody, perennial plant branching from the ground and with persistent above-ground parts]

Herb (including epiphytic) - [Mainly small plants with fleshy stems and without bark; some herbs may be slightly woody towards the base of the stems]

Vine, climber, liana - [Climbing plant using other plants or rocks and man-made structures for support]

Strangler - [Hemi-epiphytic plant that eventually envelops and strangles its host, becoming a free-standing tree]

Arborescent herb - [A non-woody plant reaching tree height e.g. banana plant]


Epiphytic (including hemi-epiphytic) - [Growing on, but not parasitic on, another plant; hemi-epiphytic plants also grown partly on the ground]

Type of climber

Tendril climber - [Climbing by support of slender, spirally coiled, climbing-organs originating from a stem, leaf or inflorescence]

Thorn/hook climber - [With thorns/hooks developed from stem or stipules allowing plant to grip other plants or surfaces]

Sucker climber - [With aerial, adhesive roots/suckers allowing the plant to climb hard surfaces such as stones and bricks]

Stem twiner - [Plant that climbs by twisting its stem round some other body (plant or man-made structure): e.g. a climbing bean]

Petiole twiner - [Plant that climbs by twisting the petioles of its leaves round some other body (plant or man-made structure)]

Climbing without specialised structures

Tendril position

From axil of leaves (base of petiole) - [Axillary: from the angle or 'armpit' between the base of the petiole of a leaf and the stem]

Opposite or at right angles to leaves - [If at right angles, this is probably Cucurbitaceae]

On leaves or leaflets - [Usually branching from the tip or from the rachis and sometimes substituting for one of the leaflets]

On inflorescences

On ends of branches

Ecological type

Mesophytic (in moderately moist environment)

Xerophytic (in dry environment)

Hydrophytic (in water, whether rooted or not)

Halophytic (in salty ground) - [Usually beside the sea in tidal salt marshes and salt flats, though occasionally on inland salt deposits]

Helophytic (in waterlogged, but not salty, ground) - [Excluding halophytes]

Aquatic habitat (fully aquatic plants)

Non-marine - [Growing in fresh water - rivers or lakes]

Marine - [Growing in sea water - sea shore and estuaries]

Nutrition type

Autotrophic - [Living independently of other organisms for its organic nutrition]

Carnivorous (including insectivorous) - [Obtaining all or part of its nourishment by trapping and digesting small animals such as insects]

Parasitic (totally or partially) - [Obtaining part of or all its nourishment from other plants by tapping into their vascular system]

Saprophytic - [Usually lacking chlorophyll and nourishing itself mainly from soluble compounds in decaying organic matter]

Chlophyll presence/absence

With chlorophyll

Without obvious chlorophyll (i.e. no green parts)


Leaf insertion (opposite, alternate etc.): detailed version

Alternate & distichous - [Leaves arranged in two alternating rows on opposite sides of a stem and thus in the same plane]

Alternate & spiral - [Leaves borne at different levels on an axis, the insertion points of successive leaves forming a spiral around the stem]

Opposite & decussate - [Leaves borne in opposite pairs, the successive pairs being borne at right angles to each other]

Opposite & not decussate - [Leaves borne in opposite pairs, the successive pairs being borne in the same plane]

Opposite (uncertain whether decussate or not)

Whorled (in basal rosette) - [Leaves borne in a ring at the same node at the base of a stem (mainly herbaceous plants)]

Whorled (not in basal rosette) - [Leaves borne in a ring at the same node along an axis]

Leaves simple or compound

Simple (not divided into leaflets and not unifoliolate)

Compound (divided into leaflets or unifoliolate) - [Unifoliolate leaves are compound leaves with only one leaflet]

Compound form

Unifoliolate (1 leaflet per leaf - easily confused with simple) - [Unifoliolate leaves are compound leaves with only one leaflet]

Bifoliolate (2 leaflets per leaf)

Trifoliolate (3 leaflets per leaf)

Pinnate (>3 leaflets attached to central rachis)

Bipinnate (pinnate, with each leaflet also pinnate)

Palmate or digitate (>3 leaflets attached to end of petiole)

Multiply compound (e.g. tripinnate, digitate with pinnate divisions)

Leaf pinnation type

Imparipinnate (with even number of leaflets)

Paripinnate (with uneven number of leaflets)

Leaf dissection (simple leaf)

Dissected (shaped into distinct lobes or sections)

Entire (not dissected, though margin may be serrate etc.)

Form of dissection (simple leaf)

Pinnatifid (similar to pinnate leaf but not divided into discrete leaflets)

Palmatifid (similar to palmate leaf but not divided into discrete leaflets)

Runcinate (divided into tooth-like lobes pointing towards base)

Spinose (divisions of leaf ending in tooth/spiny projections)

Finely dichotomously dissected (more or less)

Much-divided (e.g. bipinnatifid, tripinnatifid or digitate-pinnatifid)

Peltate leaves

Leaves peltate - [Leaves whose petioles are attached to the abaxial (lower) surface and not to the margin]

Leaf margin

Margin entire - [Having a smooth, not dissected nor toothed, margin]

Margin serrate - [Toothed with asymmetrical forwardly-pointing teeth]

Margin dentate - [Toothed with symmetrical triangular teeth pointing laterally]

Margin crenate - [Toothed with small, rounded (sometimes undulating) teeth]

Primary vein layout (in lamina of entire leaf)

Pinnately veined - [Secondary veins depart from a single primary vein (the midrib) along its length]

Palmately veined - [Several primary veins originate at the same point of the leaf base, and diverge radially from there]

Parallel-veined - [Two or more primary veins originating beside each other at the leaf base and running in parallel to the apex where they converge]

One-veined - [Venation consists of one primary vein without pronounced secondary nor tertiary venation]

Close-parallel secondary/tertiary venation

Secondary/tertiary venation close-parallel - [Veins parallel with little or no space between them giving a 'corduroy' effect]

Secondary/tertiary venation not close-parallel


Stipules present - [Leaf-like appendages usually borne at the side of the leaf insertion]

Stipules absent - [Including opposing leaves joined by a raised line, but not by a stipule as such]

Form of stipules

Scaly - [Thin and scale-like]

Spiny - [In the form of spines]

Leafy - [Usually in the form of miniature leaves, sometimes with visible venation]

Represented by glands

Ochrea - [A sheathing stipule - a stipular sheath encircling the node, some time leaving a scar]

Position of stipules

Terminal - [Encircling the leaf bud]

Inter-petiolar - [Between the petioles of two opposite leaves]

Intra-petiolar - [Between the petioles and the stems on which they are borne]

Petiole (presence/absence)

Petiolate (including 'pseudopetiolate') - [With a leaf stalk]

Sessile - [Without a leaf stalk]

Subsessile - [With almost no leaf stalk]

Perfoliate - [Leaf sessile and completely encircling the stem, which appears to grow through it]

Intra-marginal veins

Intramarginal or collecting veins present - [With veins running more or less parallel to the margin of the leaf, usually connecting the ends of the secondary vein in looping arcs]

No intramarginal or collecting veins - [Without veins running more or less parallel to the margin of the leaf]

Pulvinus (leaf)

Leaves with pulvinus - [With a more or less abrupt swelling, especially at the apex or base of a petiole]

Leaves without pulvinus - [Without noticeable swellings at the base or apex of the petiole]

Pulvinus (leaflets of compound leaf)

Leaflets with pulvinus - [Stalks of the leaflets of a compound leaf with more or less abrupt swellings, especially at the apex or base]

Leaflets without pulvinus - [Stalks of the leaflets of a compound leaf without noticeable swellings]


Cystoliths present in leaf - [Stalked, crystalline structures growing from the cell wall into the cell cavity, usually visible in the surface of the dried leaf as tiny, elongate elevations]

Cystoliths absent in leaf

Gland dots in leaf (lamina)

Leaves with visible gland dots or dashes - [Glandular, secretory structures within the structure of the leaf, appearing as pale or dark, circular or elongate blemishes when viewed against the light with a hand lens]

Leaves without visible gland dots or dashes

Gland dot shape

Glands rounded

Glands linear

Both rounded and linear glands present

Gland dot type

Gland pellucid (transparent)

Glands not pellucid (opaque)

Leaf texture

Herbaceous or membranous - [Soft, with the texture, colour and properties of a herb, often thin]

Leathery - [Tough, with the texture of leather]

Fleshy - [Having a juicy or pulpy texture; thick and firm yet soft and easily sliced]

Membranous - [Similar to a membrane, i.e. very thin]

Sclerified or modified into spines - [Leaves consisting of dead cells with woody walls or shaped into spines e.g. cacti]


Ligules present - [A leaf appendage - membranes or fringes of hairs between the sheath and the blade of a leaf]

Ligules absent

Extra-floral nectaries & glandular structures on leaf

Extra-floral nectaries/glands present - [Secretory structures (often designed to attract predators such as ants by secreting nectar) present outside the flowers, e.g. on the surface of the leaf, petiole and/or rachis]

Extra-floral nectaries/glands absent

Position of extra-floral nectaries & glandular structures

On leaf blade

On petiole

On rachis (of pinnate leaf)

Leaf hairs

Leaves with hairs - [Elongate single- or multi-celled, branched or unbranched, non-vascular, glandular or eglandular outgrowths from the epidermis; constituting the indumentum]

Leaves without hairs

Form of leaf hairs

Simple unbranched

Branched (not T-shaped)

Branched (T-shaped)

Peltate - [Having the stalk of a flattened - usually circular - structure attached centrally on its abaxial surface, not to the margin]

Stellate - [Star-shaped]

Clavate - [Club-shaped: slender at the base and gradually thickened towards the end]

Capitate or gland-tipped - [Head-like: with a globose tip like the head of a pin]

Urticating hairs

Urticating hairs present - [Stinging hairs that inject an irritant chemical on contact]

Urticating hairs absent

Leaf colour (dry specimens)

Black or blackish

Yellowish or olive-green

Other vegetative characters


Obvious exudate when cut - [Any liquid, gelatinous or resinous substance flowing from a plant, e.g. from bark slash or cut stem]

No obvious exudate when cut

Exudate colour


White or cream





Exudate discolouration

Exudate darkening rapidly on exposure - [Colour change due to oxidation after exposure to air]

Exudate not darkening rapidly

Specialised ant structures

Plant with specialised structures for housing ants - [Usually swollen hollows in the stems, petioles or in the lamina of the leaf]

Plant without specialised structures for housing ants

Odour (fresh material)

Aromatic - [Fragrant, due to the presence of essential oils]

Resinous - [Smelling like the viscous resinous substances of certain plants e.g. from pine trees; may be confused with aromatic]

Foetid - [Foul smelling or stinking]

Of citrus - [Similar to the smell of lemons or limes]

Of cloves [Similar to the smell of cloves]

Of garlic [Similar to the smell of garlic]

Of linseed oil [Similar to the smell of linseed oil]

Of liniment (methyl salicylate) - [Smelling like oil of wintergreen or linement]

Of almond (cyanogenic glycosides) - [Smelling like marzipan]

Spines or thorns

Plant armed with spines or thorns - [With sharp, needle-like projections from below the bark; or similar needle-like thickenings of leaf margin]

Plant unarmed - [Without spines or thorns]

Stem shape (transverse section of young stems)

Rounded (more or less)


Tetragonal - [Square in cross-section]


Winged or ridged stems

Stems winged or ridged - [With flattened expansions extending beyond the normal outline of a stem or with long, narrow upper sections or crests]

Stems not winged or ridged

Inflorescence structure and position

Flowers & fruits solitary or aggregated

Flowers & fruits aggregated in inflorescences - [Grouped together in diverse arrangements]

Flowers & fruits solitary - [Always emerging singly from their position on the plant]

Position of inflorescence or solitary flowers

Terminal - [Branch or shoot ending in inflorescences]

From leaf axils - [Inflorescences originate from leaf axils, i.e. from where the angle between the base of the leaf or leaf stalk and the stem]

Opposite the leaves - [Inflorescences originate from same level of stem as leaves, but on opposite side of the stem to the axis to the leaves]

From trunk (cauliflorous) - [With inflorescences borne on a well-developed trunk or major branch of the plant, rather than from among the leaves]

From leaf (epiphyllous) - [Growing on or from the leaves or the petioles]

From roots or underground storage organs

Intercalary (from base of internode in Monocotyledons) - [Inflorescences arise in an internodal position, i.e. many Monocotyledons]

Structure of inflorescence

Catkins - [A spike of more or less reduced and hanging flowers, similar to a raceme or spike but the flowers sessile on the axis or nearly so, and usually closely packed]

Corymbs - [Racemose inflorescence in which the pedicels of the lower flowers are longer than those of the flowers above, bringing all flowers to about the same level]

Cymes - [Sympodial inflorescence, with the apex of the stem axis converted into a flower, but further flowers arising successively from the axils of the bracteole/bract/prophyll immediately below it]

Fascicles - [A cluster of flowers in a leaf axil, but lacking both an axis and any obviously cymose or racemose construction]

Glomerules - [Like fascicles, but a more compact clusters of flowers]

Heads or Capitulae - [Inflorescences with sessile flowers aggregated into dense clusters, whether a racemose (more usual) or cymose; sometimes made up of disc and ray flowers]

Panicles (including thyrses) - [Racemose or cymose inflorescences in which the lateral branches themselves are branched]

Raceme - [Monopodial single axis bearing flowers on pedicels]

Spike - [Racemose single axis bearing sessile flowers]

Umbels - [Racemose inflorescences in which the pedicels arise in the same point, bringing all flowers to about the same level]

Verticillasters - [Cymose sequences of flowers arranged in whorls along one axis]

Synflorescences - [Simple inflorescences such as racemes, spikes, cymes aggregated into compound inflorescences]


Inflorescence with peduncle - [Inflorescence stalked, with part of the stalk evident below the insertion of any flowers or inflorescence branches]

Inflorescence without peduncle


Spathe present - [With a large bract surrounding an entire inflorescence, e.g. Araceae]

Spathe absent

Flowers - nature and structure

Flowers unisexual or hermaphrodite

Unisexual flowers present - [Flowers with only fertile male or female parts]

Unisexual flowers absent (flowers seemingly all hermaphrodite) - [Flowers with both fertile male parts and fertile female parts]

Perianth composition (NB! may be misleading in Monocots) - [The perianth is collectively the calyx and corolla, also used where there are two similar whorls of tepals as in most Monocotyledons]

Flower with distinct calyx and corolla (though calyx sometimes 'petaloid') - [Flowers with both sepals and petals, although the sepals may resemble petals]

Flower with calyx only (though sometimes 'petaloid') - [Flowers with sepals which may resemble petals]

Flower with corolla only - [Flower with petals, but no sepals]

Flower sequentially intergrading from sepals to petals with intermediates

Flower tepaloid (not resolvable into calyx or corolla) - [True for most Monocotyledons]

Perianth vestigial or absent - [Only rudimentary, highly reduced sepals, petals or tepals present or no visible sign of sepals, petals or tepals]

Total number of perianth parts
Number of calyx segments
Number of corolla segments
Tepals free or joined

Tepals free (polytepalous)

Tepals joined (syn-, gamo- or monotepalous)

Corolla fusion

Petals free (polypetalous - includes insertion at the mouth of a hypanthium)

All petals joined (syn-, gamo- or monopetalous)

Both joined and free petals (partially syn- or gamopetalous)

Perianth symmetry

Perianth radially symmetrical (actinomorphic) - [The perianth is symmetrical through multiple planes]

Perianth bilaterally symmetrical (zygomorphic) but not bilabiate - [The perianth is symmetrical through a single axis only, and does not have a two-lobed lip]

Perianth zygomorphic and bilabiate - [The perianth is symmetrical through a single axis only, and is divided into upper and lower lip]

Perianth asymmetrical - [The perianth is not symmetrical through any planes]


Corona present - [A ring of tissue arising from the corolla, perianth or stamen filaments of a flower, usually forming a complex structure]

Corona absent

Bracts around flowers

Bracts present around flowers - [With leafy structures at the base of the flower (or sometimes several bracts congested at the base of an inflorescence); bracts usually different in form from the foliage leaves]

Bracts absent around flowers

Nectariferous disk

Nectariferous disk present - [A nectar-secreting, fleshy ring between whorls of the floral parts or on the ovary]

Nectariferous disk absent

Spur(s) on calyx or corolla

Spur(s) present - [With a tubular pouch at the base of a petal or sepal, often containing nectar]

Spur(s) absent


Ratio of fertile stamens to inner perianth parts

Fewer than adjacent [inner] perianth whorl

Equal to number of [inner] adjacent perianth

2X number of adjacent [inner] perianth whorl (diplostemonous)

3X number of adjacent [inner] perianth whorl (triplostemonous)

>3X number of adjacent [inner] perianth whorl (polystemonous)

Number of androecial members including staminodes (male-fertile flowers)
Insertion of androecial members (male-fertile flowers)

All free of the perianth - [Anthers not attached to the petals or sepals (though may be attached at the base of a hypanthium)]

Adnate to the perianth (including perigone tube) - [Anthers attached to the petals, sepals or the wall of a tubular perianth]

Position of fertile androecial members relative to corolla

All alternating with the corolla members

All opposite the corolla members

Both alternating with and opposite the corolla members

Staminodes (presence/absence in male-fertile flowers)

Staminodes present - [Sterile stamens, ranging from minute and practically invisible to large and petaloid structures]

Staminodes absent (fertile stamens only)

Anthers (manner of dehiscence)

Dehiscing by longitudinal valves [Anthers opening longitudinally via valves to release pollen]

Dehiscing irregularly - [Anthers opening irregularly to release pollen]

Dehiscing transversely - [Anthers splitting transversely to release pollen]

Dehiscing via full-length longitudinal slits - [Anthers splitting longitudinally via full-length slits to release pollen]

Dehiscing via short slits - [Anthers opening via short longitudinal slits to release pollen]

Dehiscing via pores - [Anthers opening via circular or oval pores to release pollen]

Anthers (fixing)

Anthers dorsifixed - [Filament attached to dorsal side of anther]

Anthers basifixed or apicifixed (impeltate) - [Filament attached to base or apex of anther]

Anthers adnate to filament or other floral structures - [Anthers adnate to filament or attached without obvious filaments to petals or other floral structures]


Position of ovary

Ovary superior - [Borne above the level of attachment of the other floral parts or above the attachment of a hypanthium that is free from the ovary and itself bears the perianth segments and stamens]

Ovary inferior - [Borne below the level of attachment of the other floral parts]

Ovary partly inferior - [Stamens and perianth arising from a cup or tube (= hypanthium) that is free from the ovary but extends above its base]

Gynoecium structure

Gynoecium apocarpous (more than 1 free carpel) - [Excluding forms joined only at the styles or stigmas]

Gynoecium monomerous (1 single free carpel)

Gynoecium syncarpous (2 or more carpels at least partially joined basally)


Stigma borne on style (style present)

Stigma sessile (style absent)

Number of styles (syncarpous gynoecia)
Number of carpels
Number of locules in ovary (syncarpous gynoecia)
Gynoecium borne on gynophore or androgynophore

Gynophore or androgynophore present - [A stalk derived from the flower receptacle, bearing the gynoecium and/or stamens above the level of insertion of the stamens, gynoecium or perianth, respectively (= stipitate)]

Gynophore or androgynophore absent

Aggregate fruit from adjoining flowers

Gynoecia combining to form a multiple fruit

Gynoecia not combining to form a multiple fruit


Structure (syncarpous gynoecia representing 2 or more carpels)

Berry - [Fleshy, without a stony layer, usually several to many seeded]

Nut - [Dry, hard, indehiscent, one-seeded]

Drupe - [Fleshy, with each of the one or more seeds surrounded by a stony layer]

Capsule - [Dry, dehiscent, from two or more carpels]

Capsular-indehiscent - [Like capsule, but indehiscent]

Caryopsis - [Like achene, a dry, indehiscent, one-seeded fruit formed from an inferior ovary]

Cypsela - [Like achene but from two carpels, invested by the adnate calyx]

Samara - [Indehiscent, winged by extension of the fruit wall]

Siliqua - [Dry, bilocular, of two carpels, longitudinally two-valved]

Achene-like - [Small, hard, dry, one-seeded; like achene but from a syncarpous gynoecium]

Structure (monomeric gynoecia or individual carpels of apocarpous fruits)

Berry-like, but derived from a single carpel - [Fleshy, without a stony layer, usually several to many seeded]

Follicle - [Derived from a single carpel and dehiscing only along the ventral side]

Legume - [Derived from a single carpel and dehiscing along both sides]

Loment - [Derived from a single carpel, which at maturity breaks transversely into one-seeded segments]

Achene - [Small, hard, dry, shell hard and thin, from one free carpel]

Drupe-like, but derived from a single carpel - [Fleshy, with each of the one or more seeds surrounded by a stony layer]

Nut-like, but derived from a single carpel - [Dry, hard, indehiscent, one-seeded]

Samara-like, but derived from a single carpel - [Indehiscent, winged by extension of the fruit wall]

Structure (uncertain if gynoecium syncarpous or monomeric)

Berry or berry-like - [Fleshy, without a stony layer, usually several to many seeded]

Capsule or capsule-like (including siliqua) - [Dry, dehiscent, from two or more carpels]

Drupe or drupe-like - [Fleshy, with each of the one or more seeds surrounded by a stony layer]

Legume or legume-like (including follicle) - [Derived from a single carpel and dehiscing along along both sides]

Nut or nut-like (including achene, caryopsis, cypsella) - [Dry, hard, indehiscent, one-seeded]

Samara or samara-like - [Indehiscent, winged by extension of the fruit wall]

Aggregate or not

Fruit an aggregate on a common receptacle - [Fruit an aggregate of more or less discrete units on a common receptacle (e.g. pineapple)]

Fruit not an aggregate


Fruit dehiscent - [Fruit opening to release seeds]

Fruit lomentaceous - [Fruit breaking transversely into segments]

Fruit schizocarpous - [Fruit splitting longitudinally into non- or tardily dehiscent, fruitlike mericarps]

Fruit indehiscent - [Fruit neither opening nor breaking up in any precise fashion at maturity]

Number of seeds at maturity
Fleshiness (at maturity)

Fruit fleshy (at least partially) - [Having a juicy or pulpy texture; thick and firm yet soft and easily sliced]

Fruit not fleshy - [Without a juicy or pulpy texture; often dry, tough, and difficult to slice]

Fruit surface

Fruit surface spiny

Fruit surface spiny and ridged

Fruit surface ridged

Fruit surface smooth


Fruits winged - [Fruits with flattened wing-like projections]

Fruits not winged


Hairs on seeds

Seed conspicuously hairy

Seed not conspicuously hairy

Wings on seeds

Seeds winged - [Seeds with flattened, wing-like projections]

Seeds not winged


Aril or aril-like structure present - [An often fleshy outgrowth from the seed, partly or wholly covering it]

Aril or aril-like structure absent


Very small (less than 1mm)

Small (1-10mm)

Medium (10mm-30mm)

Large (30mm-100mm)

Very large (greater than 100mm)

Geographical region



Caribbean Islands

Central America



Guianas ( Guyana , Suriname , French Guiana )


Tropical Uruguay , Paraguay , Chile , Argentina




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