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Malvaceae

In this series, I aim to give you a quick introduction to some of the plant families found in the UK. Learning to identify plant families is a great help in identifying individual plant species you come across – if you know the family, then you know where to start looking for the species in a guide, and identifying the family is an achievement in itself. Plants are classified into families based on characteristics that they share; this is then narrowed down further into genera and then into species. So, the way to identify a plant’s family is to know these characteristic features. Today’s family is the Malvaceae, or mallow family. This family is distributed worldwide, but has its greatest level of diversity in the tropics, particularly of the Americas. It contains approximately 4200 species. They grow as herbaceous plants, shrubs and trees, annuals, biennials and perennials. The Malvaceae has great economic importance, with Gossypium (which is cotton), Theobroma cacao (which is chocolate) and Ceiba pentandra (kapok) all being in this family. Several species can be used medicinally due to the high levels or jelly-like mucilage contained in their tissues. Althaea officinalis (the marsh mallow) is an example – and yes, this is where the sweet is originally from, too. Other Malvaceae provide fibres, wood and food. The tropical Kola species (Kola nut) is chewed as a stimulant. And, of course, there are the ornamentals, like Lavatera, Althaea rosea (hollyhock) and Hibiscus species. The species encountered in the UK are either herbaceous or shrubby, and are a mix of annuals, biennials and perennials. Malvaceae flowers are open, actinomorphic, and often in shades of pink. They tend to be large and showy. They have five separate petals, which may be notched, and five sepals. The flowers possess an epicalyx, which looks like an extra ring of sepals beneath the calyx (calyx is the collective term for the sepals). The stamens in the mallow family are fused into a tube shape around the style. This tube is joined to the base of the petals. The ovary is superior, meaning it is attached above the rest of the floral parts. This ovary becomes a dry capsule or a schizocarp: a dry fruit that breaks into segments. The leaves of Malvaceae are simple, meaning they are undivided, but they are usually palmately lobed, with palmate veins. This Malva demonstrates the palmate shape, with the lobes and veins radiating out from the leaf base. At the base of the leaf stalk there are stipules: paired leaf-like structures. The leaves are arranged alternately on the stems, and the leaves and stems often possess hairs on their surface, making them downy. So, if your plant has large, pink flowers with five petals and 5 sepals, with stamens joined into a tube, an epicalyx, dry fruits that open or split, and alternate, downy, palmate leaves with stipules, try looking them up in the Malvaceae section of a field guide. See if you can find any of these species when you are out and about: Malva sylvestris, common mallow – reasonably low-growing, with dark veins on its pink flowers Malva moschata, musk mallow, with greatly dissected leaves Lavatera arborea, tree mallow – a tall, woody-based plant, also with dark veins in its flowers [Note, botanical names should always be written in italics (or underlined if handwritten)]