Like sagittate but with lobes diverging.

Hastate

Like sagittate but with lobes diverging.

A dense cluster of sessile or almost sessile flowers borne on a very short axis.

Head

A dense cluster of sessile or almost sessile flowers borne on a very short axis.

Stem finely pubescent, flowers 3-4 mm long.

Herpestris

Stem finely pubescent, flowers 3-4 mm long.

Leaves without midribs evident when examined against transmitted light; flowers yellow.

Heteranthera

Leaves without midribs evident when examined against transmitted light; flowers yellow.

Leaves entire; veins of leaf nearly parallel.

Heteranthera

Leaves entire; veins of leaf nearly parallel.

Flowers solitary; leaves small, less than 5 cm long.

Heteranthera

Flowers solitary; leaves small, less than 5 cm long.

Base of petiole not expanded; plants large, 5 dm tall or taller.

Hibiscus

Base of petiole not expanded; plants large, 5 dm tall or taller.

Plant large, over 5dm tall; flowers large, white, pink, or purplish.

Hibiscus

Plant large, over 5dm tall; flowers large, white, pink, or purplish.

Large leaves, over 5 cm broad; flowers large, over 5cm across.

Hibiscus

Large leaves, over 5 cm broad; flowers large, over 5cm across.

Submerged leaves gathered along a few centimeters of the stem; flower stalks inflated.

Hottonia

Submerged leaves gathered along a few centimeters of the stem; flower stalks inflated.

Leaves floating flat on surfacel inflourescences minute and inconspicuos.

Hydrochloa

Leaves floating flat on surfacel inflourescences minute and inconspicuos.

Leaves small, about 8 cm. in diameter or less; toothed or lobed.

Hydrocotyle

Leaves small, about 8 cm. in diameter or less; toothed or lobed.

Leaves round, often peltate; the long petiole attached near center of leaf.

Hydrocotyle

Leaves round, often peltate; the long petiole attached near center of leaf.

Leaves coming off a creeping or horizontal stem.

Hydrocotyle

Leaves coming off a creeping or horizontal stem.

Sepals united at base into a tube enclosing the ovary and later the fruit; leaves with spines in axils.

Hydrolea

Sepals united at base into a tube enclosing the ovary and later the fruit; leaves with spines in axils.

Plants aromatic when crushed; flowers blue.

Hydrotrida

Plants aromatic when crushed; flowers blue.

flowers solitary or a few in hte axils of the leaves.

Hygrophila

flowers solitary or a few in hte axils of the leaves.

Flowers with filaments connected by a funnel-like membrane.

Hymenocallis

Flowers with filaments connected by a funnel-like membrane.

Portion of the united calyx investing the fruit.

Hypanthium

Portion of the united calyx investing the fruit.

Leaf, when examined against light with lens, showing semitransparent dots; flowers yellow or pink.

Hypericum

Leaf, when examined against light with lens, showing semitransparent dots; flowers yellow or pink.

Leaves usually with a few remote teeth above the middle or at least bristle-tipped; fruit a red or black berry.

Ilex

Leaves usually with a few remote teeth above the middle or at least bristle-tipped; fruit a red or black…

Spirally overlapping.

Imbricate

Spirally overlapping.

Cut sharply, irregularly, and more or less deeply.

Incised

Cut sharply, irregularly, and more or less deeply.

Rolled inwardly toward the midrib.

Involute

Rolled inwardly toward the midrib.

Leaves large (1cm wide or wider); flowers very showy.

Iris

Leaves large (1cm wide or wider); flowers very showy.

Leaves all from a hardened base or from a single point; base of leaves with spore sacs.

Isoetes

Leaves all from a hardened base or from a single point; base of leaves with spore sacs.

Sepals not pubescent or only slightly so; fruit a linear, two grooved capsule; leaves elliptic.

Itea

Sepals not pubescent or only slightly so; fruit a linear, two grooved capsule; leaves elliptic.

Plants stuff; rooting along the stem; leaves stiff and often fascicles.

Juncus

Plants stuff; rooting along the stem; leaves stiff and often fascicles.

Flowers or fruits individually manifest; parts in threes.

Juncus

Flowers or fruits individually manifest; parts in threes.

Sheaths at base of stem merely overlapping.

Juncus

Sheaths at base of stem merely overlapping.

Leaves narrow, mostly less than 1 cm.

Juncus

Leaves narrow, mostly less than 1 cm.

Flowers large, showy yellow; fruit a four angled capsule.

Jussiaea

Flowers large, showy yellow; fruit a four angled capsule.

Capsule or calyx tube long and slender, ovre 1.5cm long; stamens.

Jussiaea

Capsule or calyx tube long and slender, ovre 1.5cm long; stamens.

Flowers irregular, purplish.

Justicia

Flowers irregular, purplish.

Possessing a central ridge as a boat.

Keeled

Possessing a central ridge as a boat.

Irregularly cut as if torn.

Lacerate

Irregularly cut as if torn.

Shaped like a spear head, broadest near base, tapering to apex, and several times as long as broad.

Lanceolate

Shaped like a spear head, broadest near base, tapering to apex, and several times as long as broad.

Leaflets usually 3, very prominently toothed.

Leaflets

Leaflets usually 3, very prominently toothed.

Leaflets usually more than 3; not prominently toothed.

Leaflets

Leaflets usually more than 3; not prominently toothed.

Stems weakly arching; leaves lanceolate; flowers showy purplish.

Leaves

Stems weakly arching; leaves lanceolate; flowers showy purplish.

Leaves remotely toothed, acumnate at apex; flowers appearing before the leaves.

Leaves

Leaves remotely toothed, acumnate at apex; flowers appearing before the leaves.

Compound Leaves

Compound Leaves

Compound Leaves

Spikelets very strongly flattened.

Leersia

Spikelets very strongly flattened.

Plant body inconspicuously nerved, roolets one per disk.

Lemna

Plant body inconspicuously nerved, roolets one per disk.

Leucothoe

Leucothoe

Leucothoe

Leaves mostly differentiated into blades and petioles.

Limnobium

Leaves mostly differentiated into blades and petioles.

Long and narrow and with parallel sides.

Linear

Long and narrow and with parallel sides.

Plants decumbent at base and usually rooting at the lower nodes.

Lippia

Plants decumbent at base and usually rooting at the lower nodes.

With projection or divisions.

Lobed

With projection or divisions.

Upper flowers with stamens only.

Lophotocarpus

Upper flowers with stamens only.

flowers solitary in the axils of the leaves; leaves less than 3.5cm long.

Ludwigia

flowers solitary in the axils of the leaves; leaves less than 3.5cm long.

Capsule or calyx tube short and stout, not reflexed.

Ludwigia

Capsule or calyx tube short and stout, not reflexed.

A flowering plant belonging to the Amaryllidaceae genus.

Stenbergia Lutea

A flowering plant belonging to the Amaryllidaceae genus.

Stems 4-angled; flowers small, in dense clusters in the axils of the leaves.

Lycopus

Stems 4-angled; flowers small, in dense clusters in the axils of the leaves.

Flowers small, white, gathered in dense, sessile clusters in the axils of the leaves.

Lycopus

Flowers small, white, gathered in dense, sessile clusters in the axils of the leaves.

Flowers purple; plant usually corky at base.

Lythrum

Flowers purple; plant usually corky at base.

Leaves silvery beneath.

Magnolia

Leaves silvery beneath.

Inflourescence made up of bony, bead-like joints.

Manisuris

Inflourescence made up of bony, bead-like joints.

An illustration of a flowering branch of common mare's tail; a, flower before athesis; b, flower after athesis; c, fruit. The Common Mare's tail, Hippuris vulgaris, is a common aquatic plant of Eurasia and North America. The species is also sometimes called Horsetail, a name which is better reserved to the Horsetails of genus Equisetum. These are unrelated to the water plant, though there is some resemblance in appearance.

Common Mare's Tail

An illustration of a flowering branch of common mare's tail; a, flower before athesis; b, flower after…

Leaves crowded on stem; flowers three petaled, pink and fairly conspicuous.

Mayaca

Leaves crowded on stem; flowers three petaled, pink and fairly conspicuous.