1Petals and stamens caducous. Stamen fascicles, styles and ovary loculi 5. Broad-leaved shrubs, without black glands.
1'Petals and stamens persistent. Stamen fascicles 5-3 (i.e. 2 + 2 + 1) or stamens apparently afasciculate. Styles 3-5. Ovary loculi 1-4. ± Ericoid shrubs or shrublets or herbs, often with black glands on various parts of the plant.
2Styles free or partially united. Anthers dorsifixed. Inflorescence up to 3 nodes long. Sect. Ascyreia CHOISY.
2'Styles completely united. Anthers apparently basifixed. Inflorescence up to 14 nodes long. Sect. Takasagoya (Y. KIMURA) N. ROBSON.
3Styles free. Leaves laxly or scarcely reticulate beneath.
3'Styles united almost to the apex. Leaves densely reticulate beneath.
4Sepals acute to subacute. Petals (20-)25-45 mm long. Branches erect or arching, not frondose.
4'Sepals rounded. Petals 9-18 mm long. Branches arching, sometimes frondose.
5Capsule longitudinally vittate (scarcely so in H. beccarii subsp. steenisii). Placentation axile to parietal. Black glands usually present. Petals pale yellow (flavus) to golden yellow (aureus). Shrubs or herbs.
5'Capsule smooth, not vittate. Placentation parietal. Black glands absent. Petals usually apricot yellow (armeniacus) to orange (aurantiacus), sometimes red-tinged; small herbs with quadrangular stems. Sect. Brathys (MUTIS ex L.f.) CHOISY.
6Plant an erect or ± straggling shrub or woody herb. Styles 3-5, equalling or shorter than the ovary. Placentation axile to parietal. Sect. Humifusoideum R. KELLER.
6'Plant a perennial or annual herb or, if suffrutescent, then styles 1.4-1.7 times as long as the ovary. Styles 3 (4). Placentation axile.
7Flowers solitary, not in dichasial cymes nor with shoots in the axils of the uppermost leaf pair.
7'Flowers in regular or irregular dichasial cymes or, if solitary, then with shoots in the axils of the uppermost leaf pair.
8Leaves cuneate at the base, linear to elliptic or ovate-lanceolate, rarely broader, with laminar pale glands almost always linear towards the leaf base.
8'Leaves rounded to cordate at the base, narrowly ovate or ovate-triangular or elliptic to subcircular, with laminar pale glands linear towards the leaf base only or wholly punctate.
9Leaves spreading or ascending, 8-12 mm long, flat. Styles 2½-3 mm long.
9'Leaves imbricate, ± appressed, 2-9 mm long, flat or incurved. Styles 1½-2½ mm long.
10Leaves flat, ovate-lanceolate to narrowly elliptic-oblong, with laminar glands mostly interrupted to punctate. Placentation axile.
10'Leaves incurved, narrowly elliptic or lanceolate-elliptic to linear with laminar glands mostly linear. Placentation parietal.
11Flowers always solitary with shoots in the axils of the uppermost leaf pair; leaves with laminar pale glands linear, often with parallel rows of dots. Styles 3.
11'Flowers in regular or irregularly dichasial cymes; leaves with laminar pale glands linear or punctate, without parallel rows of dots. Styles 3-5.
12Stem internodes 2-4(-6)-lined, at least when young. Stamen fascicles 3-5 or stamens not obviously in fascicles. Flowers solitary or with shoots in uppermost leaf axils. Suffrutescent or wiry herbs. Sect. Humifusoideum R. KELLER.
12'Stem internodes terete. Stamen fascicles 3. Flowers in dichasial or monochasial cymes. Tufted or straggling perennial or annual herbs. Sect. Hypericum.
13Plant a suffrutescent herb with erect or ascending stems. Leaves sessile. Flowers 2-3 cm ø.
13'Plant a perennial herb with diffuse wiry branches. Leaves petioled. Flowers¾-1 cm Ø
14Sepal apex rounded. Petiole absent or up to 0.7 mm long. Perennial.
14'Sepal apex acute. Petiole 1-3 mm long. Annual.
15Petals c. 1.3 times as long as sepals. Sepals lanceolate to narrowly elliptic, acute or subacute. Stamens 30-50. Leaves mostly ovate-lanceolate to linear-lanceolate or narrowly oblong. Erect perennial or annual.
15'Petals c. 0.85—1(—1.3) times as long as sepals. Sepals narrowly oblong to elliptic or obovate, acute to rounded. Stamens 5-30. Leaves very variable in shape. Erect to prostrate annual (always?)