Althaea

Linnaeus

Sp. Pl. 2: 686. 1753

Gen. Pl. ed. 5, 307. 1754

Common names: Marshmallow guimauve
Introduced
Etymology: For Althaea, wife of King Oeneus of Aetolia or Calydon
Treatment appears in FNA Volume 6. Treatment on page 231. Mentioned on page 218, 228, 286.
Herbs, annual or perennial, usually hairy, hairs stellate or simple, not viscid. Stems erect to decumbent. Leaves: stipules persistent or caducous, subulate or linear to lanceolate, simple to 2 or 3-fid; blade reniform, deltate-ovate, or ovate, bluntly or acutely lobed or palmately parted, base cuneate, truncate, obtuse, or cordate, margins crenate to coarsely dentate or serrate. Inflorescences axillary, solitary flowers or in 2–4-flowered fascicles, these concentrated on ends of stems and branches; involucel present, bractlets persistent, 6–9(–12), connate basally. Flowers: calyx not or slightly accrescent, not inflated, campanulate, 5-lobed, lobes connate basally, not ribbed, ovate or lanceolate, apex obtuse, acuminate, or apiculate; corolla rotate to wide-campanulate, white or pink to lilac-purple or bluish, petals asymmetric, schizocarpic achenes, erect, not inflated, reniform to orbicular, rounded to angled, unwinged, not or slightly indurate, stellate-pilose-hairy or glabrous, indehiscent; mericarps [8–]10–20[–24], 1-celled. Seeds 1 per mericarp, reniform-round, minutely rugulose, glabrous. x = 21.

Distribution

Europe, w, c Asia (Mediterranean region).

Discussion

Species 6–12 (4 in the flora).

Two of the species of Althaea in the flora area occur in cultivation and rarely escape. The perennial species generally have stellate pubescence and the annual species generally have simple hairs; both have pink to purple anthers; the annuals are thought by some to be better placed within the genus Malva. Althaea is very similar to Alcea, and the latter has been combined with it by various authors. Hybrids between the two (×Alcathaea Hinsley) have been described, as have hybrids between Malva and Althaea (×Malvalthaea Iljin). See discussion under 13. Alcea for more information.

References

None.

Key

1 Annuals, hispid-hirsute; petals to 1 1/2 times as long as calyx; staminal columns glabrous; anthers pale pink to almost white (yellow). Althaea hirsuta
1 Perennials, stellate-hairy; petals (1.1–)2–3 times as long as calyx; staminal columns clavate-hairy or glabrous; anthers purple > 2
2 Leaves unlobed or at most 3(–5)-lobed 1/2 to midrib; mericarps densely stellate-hairy. Althaea officinalis
2 Leaves palmately divided 1/2+ to midrib, 5-lobed; mericarps glabrous or stellate-hairy > 3
3 Peduncles many-flowered; mericarps stellate-pilose-hairy. Althaea armeniaca
3 Peduncles 2–3-flowered; mericarps glabrous. Althaea cannabina