| b. Vittæ present. | |
| Tufted or diffuse. Leaves much dissected. Fruit narrowed above, nearly terete | 6. Oreomyrrhis. |
| Aquatic. Stem creeping. Leaves terete, fistular, septate | 7. Crantzia. |
| ** Umbels regularly compound. Vittæ present (obscure in some). Primary ridges of the fruit alone conspicuous. | |
| Littoral. Stems decumbent. Involucre wanting. Carpels nearly terete | 5. Apium. |
| Leaf-segments ending in acicular or spinous points. Umbels in erect spikes or panicles | 8. Aciphylla. |
| Leaves pinnate or decompound. Umbels terminal. Carpels with 3–5 narrow equal wings | 9. Ligusticum. |
| Leaves pinnate or 1–3-foliolate in the New Zealand species. Carpels with 2 broad lateral wings | 10. Angelica. |
| *** Umbels regularly compound. Secondary ridges of the fruit prominent, covered with bristles | 11. Daucus. |
1. HYDROCOTYLE, Linn.
Prostrate herbs. Stems long, slender, rooting at the nodes, often matted. Leaves orbicular or reniform, deeply cordate or peltate, palmately toothed or lobed or divided, rarely entire, long-petioled; stipules small, scarious. Umbels simple, small; involucral leaves usually inconspicuous or wanting. Flowers small, sometimes unisexual. Calyx-teeth minute or obsolete. Petals entire, valvate or imbricate. Fruit laterally compressed, with a narrow commissure; carpels flat, placed edge to edge, with 1 or more prominent ribs on each face; vittæ wanting. Seed straight, laterally compressed.
A genus of about 80 species, spread over the warm and temperate regions of the world, but most numerous in the Southern Hemisphere. Of the 9 New Zealand species 1 has a wide range in tropical and subtropical countries, another is found in North and South America, 2 occur in Australia, the remainder appear to be endemic.
| Section I. (Euhydrocotyle). Involucral bracts narrow or inconspicuous or wanting. Petals valvate. Carpels without secondary ribs or reticulatiotis. | |
| Leaves deeply 3–7-lobed. Peduncles exceeding the leaves. Fruits on long slender pedicels | 1. H. elongata. |
| Leaves 3–5-foliolate; leaflets cuneate. Peduncles shorter than the leaves. Umbels 2–6-flowered | 2. H. tripartita. |
| Leaves 3–7-lobed almost to the base. Umbels 20–40 flowered; peduncles longer or shorter than the leaves | 3. H. dissecta. |
| Leaves thin, with 5–7 shallow lobes. Umbels 3–7-flowered, sessile or on very short peduncles (sometimes half as long as the petioles in var. heteromerta) | 4. H. americana. |
| Glabrous or nearly so. Leaves obscurely 3–7-lobed. Umbels 3–8-flowered. Carpels large, flat, with a broad dorsal wing | 5. H. pterocarpa. |
| Pilose or nearly glabrous. Leaves obscurely 3–7-lobed. Umbels 5–12-flowered. Carpels rounded on the dorsal edge | 6. H. novæ-zealandiæ |
