2.
Tiarella trifoliata
Linnaeus, Sp. Pl. 1: 406. 1753.
Three-leaf foamflower
Flowering stems
10-70 cm.
Leaves
simple or 3-foliolate; cauline leaves 1-4, simple or 3-foliolate; petiole 0.2-20 cm; blade 2-10 × 3-15 cm.
Inflorescences
narrow panicles, 15-70-flowered, 10-70 × 1-5 cm.
Pedicels
subtended by finely dissected bracts, 0.1-1.2 cm, glandular-stipitate.
Flowers:
hypanthium campanulate, 2-3 mm, glandular-stipitate; perianth somewhat bilaterally symmetric; sepals spreading at anthesis, reflexed in fruit, 1-1.5 × 0.5-0.8 mm; petals caducous, spreading, linear or subulate, unlobed, 2-3 × 0.5 mm, base clawed, apex attenuate; stamens unequal, 3-4 mm and 1.8-2.5 mm; anthers oblong, 0.4-0.5 mm.
Capsules
0.6-0.9 cm.
Seeds
2-6, ovoid, 1.2-1.5 × 0.6-0.9 mm.
Varieties 3 (3 in the flora): w North America.
Varieties of
Tiarella trifoliata
have overlapping ranges and differ from each other in leaf form and marginal dissection. Their floral features are stable throughout. They were previously suspected of hybridizing when sympatric. They are differentiated along elevational gradients and often remain distinct in sympatric populations.
