The Umbelliferae, as we see them here, are herbaceous, with hollow, often striated stems, usually more or less divided leaves, and no stipules.  Occasionally we meet a genus, like Eryngium or Hydrocotyle, with leaves merely toothed or lobed.  The petioles are expanded into sheaths; hence the leaves wither on the stem.  The flowers are usually arranged in simple or compound umbels, and the main and subordinate clusters may or may not be provided with involucres and involucels.  To this mode of arrangement there are exceptions.  In marsh-penny-wort (Hydrocotyle) the umbels are in the axils of the leaves, and scarcely noticeable; in Eryngium and Sanicula they are in heads.  The calyx is coherent with the two-celled ovary, and the border is either obsolete or much reduced.  There are five petals inserted on the ovary, and external to a fleshy disk.  Each petal has its tip inflexed, giving it an obcordate appearance.  The common colors of the corolla are white, yellow, or some shade of blue.  Alternating with the petals, and inserted with them, are the five stamens.

The fruit, upon which so much stress is laid in the study of the family, is compound, of two similar parts or carpels, each of which contains a seed.  In ripening the parts separate, and hang divergent from a hair-like prolongation of the receptacle known as the gynophore.  Each half fruit (mericarp) is tipped by a persistent style, and marked by vertical ribs, between or under which lie, in many genera, the oil tubes or vittae.  These are channels containing aromatic and volatile oil.  In examination the botanist makes delicate cross sections of these fruits under a dissecting microscope, and by the shape of the fruit and seed within, and by the number and position of the ribs and oil tubes, is able to locate the genus.  It, of course, requires skill and experience to do this, but any commonly intelligent class can learn the process.  It goes without saying, and as a corollary to what has already been stated, that these plants should always be collected in full fruit; the flowers are comparatively unimportant.  Any botanist would be justified in declining to name one of the family not in fruit.  An attempt would often be mere guesswork.

In this family is found the poison hemlock (Conium) used by the ancient Greeks for the elimination of politicians.  It is a powerful poison.  The whole plant has a curious mousy odor.  It is of European origin.  Our water hemlock is equally poisonous, and much more common.  It is the Cicuta maculata of the swamps—­a tall, coarse plant which has given rise to many sad accidents. AEthusa cynapium, another poisonous plant, known as “fool’s parsley,” is not uncommon, and certainly looks much like parsley.  This only goes to show how difficult it is for any but the trained botanist to detect differences in this group of plants.  Side by side may be growing two specimens, to the ordinary eye precisely alike, yet the one will be innocent and the other poisonous.