Aquatic and Wetland Vascular Plants of the Northern Great Plains
Ammannia L. -- Toothcup
Usually small, simple to widely branched, glabrous annuals. Leaves opposite or an occasional pair subopposite, linear to oblong or oblanceolate, mostly auriculate or cordate and clasping at the base. Flowers small, 4-merous, (1)3-many in axillary cymes, these sessile or pedunculate. Calyx tube urceolate to campanulate in flower, subglobose in fruit, often strongly 8-ribbed in flower, the 4 lobes low and broadly triangular, alternating with 4 short, thickened appendages or these sometimes absent; petals normally 4, early deciduous, lavender to rose pink or rose-purple, drying purple; stamens 4(-12), exserted; style persistent, exserted in fruit. Capsules globose, smooth, membranous, irregularly dehiscent; seeds numerous, ovoid, ca. 1 mm long.
Reference:
Graham, S. A. 1979. The origin of Ammannia X coccinea Rottb. Taxon 28:169-178.
| Lead | Characteristic | Go To |
| 1 | Plants slender, with axillary cymes borne on filiform peduncles 3-9 mm long; flowers many, with mostly at least 7 per axil; capsules mostly 2.5 mm or less in diameter. | A. auriculata |
| 1 | Plants robust, with axillary cymes sessile or borne on stout peduncles to 4(-9) mm long; flowers mostly (1)3-5 per axil; capsules mostly 3.5 mm or more in diameter. | Lead 2 |
| 2 | Inflorescences sessile or nearly so, mostly with 1-3 flowers per axil; petals pale lavender and anthers yellow in fresh flowers; capsules 4-6 mm in diameter. | A. robusta |
| 2 | Inflorescences on short to prominent peduncles, rarely sessile, mostly with 3-5 flowers per axil; petals deep rose-purple or rose with a deep purple midvein and anthers deep yellow in fresh flowers; capsules mostly 3.5-5 mm in diameter. | A. coccinea |
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