Dr M’s Top Twenty Flowering Plant Families: Apiaceae

It’s high time for another of Dr M’s top 20 flowering plant families, this time it is the turn of the Apiaceae.

Maybe you know this family by the older name – Umbelliferae – a name very evocative of the typical inflorescence – the umbel or umbrella-like inflorescence.

Commonly known as the Carrot family with 434 genera and 3,700 species World-wide, many are aromatic herbs with a variety or culinary and medicinal uses (including famous and pretty effective poisons such as Hemlock!).

The Apiaceae in brief:

• In Britain mainly annual or perennial herbs with alternate leaves and no stipules.
• Leaves compound – often ternate or pinnate with sheathing petioles, with hollow stems, plants often strong smelling, many are food or medicinal plants.
• Flowers in compound umbels – simple or compound often with bracts at the base of primary or secondary umbels
• Flowers with tiny calyx of 5 teeth or absent, corolla with 5 free white or pink or yellow petals often notched and unequal, 5 stamens and 2 styles usually swollen at base (=stylopodium).
• Ovary inferior of 2 fused carpels which ripens into 2 mericarps – 2 single seeded segments compressed together, separating when ripe often flattened and adorned with ridges and wings (very photogenic!).

Example of Apiaceae:

This is a large a family in Britain with 50 different genera and numerous species, and can be daunting to the beginning botanist.  But flower colour is a helpful start (separating yellow (e.g. Pastinaca sativa – Parsnip) and white flowering species (e.g. Daucus carota – Wild Carrot). Then the shape of the leaves (stem leaves and leaves in the basal rosette can be quite different so check both types) and the shape and ornamentation of the ripe fruits (mericarps) are important characters.

Daucus carota (Wild Carrot)

Erect, often branched and roughly hairy (hispid) biennial reaching up to 1 m tall but often much shorter especially in nutrient poor habitats. Stem is solid and the ridged, the basal leaves 3-pinnate with oval-lanceolate leaflets 5-8 mm long.  The umbels are 3-7 cm wide with many bristly bracts forming a ruff below the primary umbel. The flowering time is June to August and the flowers are white and 2-3 mm across but often with a single central dark red flower (a curious feature to which one can only ask why?!). The fruit is 2.5-4 mm across, hispid with 4 spiny ridges on each carpel.

There are two sub-species.  Daucus carota ssp. carota has umbels concave in fruit and grows in grassland, roadsides usually inland, and Daucus carota ssp gummifer has more glossy, even slightly fleshy leaves, with blunter leaflets and umbels convex in fruit and grows in grassland on cliffs near the sea.

The cultivated carrot is ssp. sativus with the familar orange, fleshy, swollen taproot whereas in the two wild ssp. smell very much of carrot but the taproot is white and starchy and tough not fleshy.

Heracleum sphondylium (Hogweed)

Tall, roughly hairy (hispid) biennial, reaching 2 metres tall. Stems hollow and ridged and with downward pointing hairs. Leaves are coarsely pinnately lobed up to 15 cm long, the lower ones stalked. Umbels are 5-15 cm wide usually with no bracts (at base of primary umbels) but bracteoles (at base of secondary umbels) bristle-like and down-turned. Flowering time is June to September, and the flowers are white or pinkish and malodorous (with unpleasant aroma of ammonia, rather like a public toilet) and attracting pollinating insects such as flies. Petals notched and asymmetric (unequal). Fruits 7-8 mm oval and whitish green turning brown and papery as they ripen, with linear oil bodies (markings).

Hogweed is a very common plant of grassland, roadsides, hedgebanks and woodland.

As with the related but much much bigger Giant Hogweed, some people experience an allergic reaction if the the sap contacts skin, especially with exposure to sunlight.

Check Dr M’s ID video for another white Umbellifer.