Rhamnaceae

Rhamnaceae is in the order Rosales.

 

Most species are tree or shrubs. Leaves usually alternate. Stipules are usually present.

Spines are often present eg. Rhamnus and Paliurus.

The flowers are often small. The flowers often have a prominent disk. The 4-5 stamens are opposite the petals. The ovary has 2-4 styles. The fruits are fleshy drupes or nuts.

Rhamnaceae are recognisable by their toothed, stipulate leaves that often have strong, parallel secondary veins and scalariform tertiary venation. Their flowers have stamens opposite the often clawed petals, a hypanthium with a nectary inside, and a valvate calyx with sepals that are ridged down the middle on their inner surfaces. The capsules are dehiscent, the fruit wall often separating into two layers with the inner woody layer twisting as dehiscence occurs; there is usually no columella. There is often a conspicuous rim on the ouside of the fruit towards the base marking the place where the hypanthium was attached. In taxa such as Gouania with largely inferior ovaries the calyx, etc., is persistent. In lianes the shoots often develop somewhat laterally in the leaf axils and may have a bud at the very base.

Berchemia

Colubrina

Gouania

Helinus

Lasiodiscus

Phylica

Scutia

Zyzyphous

 

 

Hydrocharitaceae

Hydrocharitaceae is in Alismatales. Its flowers are usually dioecious with 3 free sepals and 3 petals (sometimes absent) . The ovary is inferior.

Hydrocharis (UK: Frogbit)

Leaves with long petioles and cordate blades. Roots hanging in water.

Stratiotes (UK: Water-soldier)

Sessile leaves, leaves in a basal rosette, leaves sharply serrate. Conspicuous white petals.

Egeria (UK: Large-flowered Waterweed)

Leaves borne along the stems, whorled leaves, petals white and bigger than 5mm

Elodea

Leaves in whorls of 3-4, rooted in mud. (Only female plants occur in Britain)

Hydrilla

 

Lagerosiphon

Sessile leaves, leaves borne along the stems, leaves not strictly arranged; variously whorled to spiral

Potamogetonaceae

APG 3 places Potamogetonaceae in Alismatales:

Potamogetonaceae contains pondweeds.

Potamogetonaceae are distinguished from other pondweeds by their four tepals and four stamens.

In Potamogeton, leaf arrangement tends to be alternate.

In Groenlandia, leaf arrangement tends to be opposite

The inflorescence is usually a stalked spike or an axillary cluster of flowers.

The ovary is superior. The fruit is a drupe or a berry.

Potamogetonaceae are aquatic plants most of which have more or less petiolate leaves with midrib and cross veins; there is usually a conspicuous basal ligule. The inflorescence is densely spicate and the flowers have small tepals appearing to be borne on the backs of the stamens.

 

Acanthaceae

Acanthaceae is firmly within Lamiales.

Herbs, shrubs or twiners with stems that are often angled or winged. Usually with distinct ridges around the stem at the nodes. Stems and leaves often with cystoliths looking like small white rods. Leaves opposite. No stipules. Bracts and bractioles in the inflorescence. Calyx 4-5 lobed and fused at least at the base. Calyx often zygomorphic with unequal lobes. Four stamens or two stamens. Fruit a 2-locular loculicidal capsule (splitting lengthways).

Mendoncia

Fruit a 1-seeded drupe.

Saintpauliopsis

Retinacula lacking or papilliform, bracts alternate and fused to pedicels, corolla distinctly two lipped and small (less than 1cm), plant with trailing stems

Anisosepalum

Retinacula lacking or papilliform, bracts alternate and fused to pedicels, corolla distinctly two lipped and longer than 1cm, plant with erect stems

Elytraria

Retinacula lacking or papilliform, bracts alternate and not fused to pedicels, corolla almost radially symmetrical, leaves in basal or apical rosette, calyx 5-lobed.

Nelsonia

Retinacula lacking or papilliform, bracts alternate and not fused to pedicels, corolla almost radially symmetrical, leaves dispersed along elongated stems, calyx 4-lobed.

Pseudocalyx

Retinacula lacking or papilliform, bracts opposite, calyx a rim with many lobes, capsule more than 1.5cm long with a long beak, stellate hairs, anthers opening with apical pores.

Thunbergia

Retinacula lacking or papilliform, bracts opposite, calyx a rim with many lobes, capsule more than 1.5cm long with a long beak, anthers opening by slits.

Crossandra

Retinacula prominent. Four fertile stamens, anthers with 1 thecae, plant without cystoliths, stamens included in corolla tube, corolla hairy on outside

Stenandrium

Retinacula prominent. Four fertile stamens, anthers with 1 thecae, plant without cystoliths, stamens included in corolla tube, corolla glabrous on outside, leaf base cordate

Sclerochiton

Retinacula prominent. Four fertile stamens, anthers with 1 thecae, plant without cystoliths, stamens exserted with flattened bony filaments, calyx with 5 lobes.

Acanthus

Retinacula prominent. Four fertile stamens, anthers with 1 thecae, plant without cystoliths, stamens exserted with flattened bony filaments, calyx with 4 lobes, all four filaments similar

Blepharis

Retinacula prominent. Four fertile stamens, anthers with 1 thecae, plant without cystoliths, stamens exserted with flattened bony filaments, calyx with 4 lobes, leaves in whorls of four, two filaments flattened, seeds with hygroscopic hairs

Lepidagathis

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 4-lobed, inflorescence distincly dorsiventral with flowers and bracts on one side and sterile bracts on the other side, lower lip of corolla 3-lobed.

Barleria

Retinacula prominent. Four or two fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 4-lobed, lower lip of corolla never 3-lobed.

Duosperma

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths,calyx 5-lobed, capsule with two seeds

Asystasia

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four seeds, flowers in 1-sided racemose cymes.

Crabbea

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four seeds, flowers in globose heads with large bracts that are sometimes spiny

Ruellia

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four or more seeds, corolla radially symetrical

Hygrophila

Retinacula prominent. Four or two fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four or more seeds, corolla distinctly two lipped, flowers in dense heads surrounded by spiny modified branches

Dyschoriste

Retinacula prominent. Four or two fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four seeds, corolla distinctly two lipped, lower lip with stiff retrorse hairs

Whitfieldia

Retinacula prominent. Four fertile stamens, anthers with 2 thecae, plant with cystoliths, calyx 5-lobed, capsule with four seeds, flowers single, each supported by a single bract, corolla over 3cm long, seeds glabrous

Ruspolia

Retinacula prominent. Two fertile stamens, glabrous seeds, stamens with 1-thecous anthers, stamens included in corolla tube or not much exserted

Dicliptera

Retinacula prominent. Two fertile stamens, glabrous seeds, stamens with 2-thecous anthers, whole inflorescence cymes held between two bracts

Isoglossa

Retinacula prominent. Two fertile stamens, glabrous seeds, stamens with 2-thecous anthers, each flower supported by a single bract, the two anther thecae attached at the same height or at different heights

Rhinacanthus

Retinacula prominent. Two fertile stamens, glabrous seeds, stamens with 2-thecous anthers, each flower supported by a single bract, the two anther thecae attached at different heights

Justicia

Retinacula prominent. Two fertile stamens, glabrous seeds, stamens with 2-thecous anthers, each flower supported by a single bract, the two anther thecae attached at different heights, stamens exserted, lower anther theca with distinct appendage