Order XXXIII. UMBELLIFERÆ.
Herbs, very rarely climbing or shrubby, often aromatic when bruised. Stems often grooved or channelled, solid or hollow. Leaves alternate, usually much cut and divided but sometimes simple and entire; petiole dilated and sheathing at the base; stipules wanting (except in Hydrocotyle). Flowers small, hermaphrodite or occasionally polygamous, in terminal or lateral umbels which are either simple or compound. Umbels usually furnished at the base with a ring of bracts, those below the primary (or general) umbel forming the involucre, those below the secondary (or partial) ones constituting the involucel. Calyx aduate to the ovary, limb either obsolete or 5-toothed. Petals 5, inserted at the margin of an epigynous disc, the outer often larger, imbricate or valvate, usually infiexed at the tip. Stamens 5, epigynous; filaments curved inwards. Disc epigynous, often 2-lobed and confluent with the base of the styles. Ovary inferior. 2-celled; styles 2, distinct; ovules 1 in each cell, pendulous. Fruit of 2 dry indehiscent carpels cohering by their inner faces (commissure), when ripe separatmg from a filiform central axis (carpophore), from the top of which they often remain suspended for a time. Each carpel (mericarp) generally bears 5 longitudinal ridges, sometimes expanded into wings. In the spaces or furrows between the ridges, and imbedded in the pericarp, are one or more longitudinal oil-canals (vittæ). Secondary ridges are also sometimes placed between the primary ones. Seeds 1 to each carpel, pendulous; albumen abundant, horny; embryo minute, next the hilum, radicle superior.
A very large and extremely distinct order, represented all over the world, but most plentiful in western Asia, south Europe, and north Africa; rarer in the tropics and in the south temperate zone. Genera about 160; species estimated at 1500. The properties of the order are extremely varied. Several species secrete a poisonous and narcotic acrid sap, as hemlock, fool's parsley, water drop-wort, &c. Others are characterized ty the presence of a gum-resin, as Asafœtida and Galbanum. Many species produce aromatic and carminative fruits, as caraway, coriander, dill, &c. The chief edible species are the carrot and parsnip, where the roots alone are eaten; and celery, parsley, and fennel, where the leaves and stems are employed. Of the 11 New Zealand genera, Aciphylla and Actinotus extend to Australia; Azorella and Oreomyrrhis occur in South America and the Antarctic islands as well. The remaining 7 are all widely distributed.
| * Umbels simple (sometimes irregularly compound in Azorella). | |
| a. Vittæ absent. | |
| Creeping herbs with scarious stipules. Fruit laterally much compressed | 1. Hydrocotyle. |
| Tufted or creeping. Fruit hardly compressed, subquadrate | 2. Azorella. |
| Leaves and involucres spinous. Umbels contracted into a compact spike or head | 3. Eryngium. |
| Tufted or creeping. Ovary 1-celled, 1-ovuled. Carpel solitary | 4. Actinotus. |
