Triodanis perfoliata
clasping Venus's looking glass
SunFull Sun – Part Shade
Overview
Triodanis perfoliata is an upright annual native across much of North America, growing 6-30 inches (15-75 cm) tall on slender, often unbranched stems. Rounded, shell-shaped leaves clasp the stem at their bases, so the stem appears to pass through them, the feature behind the name clasping Venus's looking glass. Violet-blue flowers about 0.5-0.75 inch (1.2-2 cm) wide open in the leaf axils up the stem, each with five spreading lobes. The lower flowers usually stay closed and self-pollinate without opening, while the upper ones open to cross-pollinate; both set seed in small capsules that release through pores in the side. T. perfoliata grows in open disturbed ground, fields, lawns, roadsides, and thin rocky soils, often as a weed of cultivated land. It tolerates poor, dry soil in full sun to light shade and finishes its cycle quickly in spring and early summer. The plant is short and slender, reading as a wildflower of meadows rather than a border specimen. It dies after seeding within a single season.
Native Range
Native to North America, found across most of the United States and into southern Canada and Mexico. It grows in fields, roadsides, lawns, woodland edges, and other open disturbed ground.Suggested Uses
Used in meadow plantings, native wildflower mixes, and naturalized open areas on poor soils. Its small flowers suit informal settings and self-sowing wildflower patches rather than formal beds.How to Identify
Appearance
Size & Dimensions
Height6" - 2'6"
Width/Spread2" - 6"
Bloom Information
Violet-blue flowers open from late spring into summer, generally May through August. The lower, self-pollinating flowers form first and never open fully, while the upper flowers open to insect pollinators. Seed capsules ripen and shed through small side pores as the plant matures.
Detailed Descriptions
Foliage Description
GreenGrowing Conditions
Sun Requirements
Requires 5-9 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Grow T. perfoliata in full sun to light shade in average to dry, well-drained soil. Sow seed directly in fall or early spring, since it self-sows readily once established. The plant tolerates poor, thin, and rocky soils and needs little or no added water. It needs no fertilizer and grows quickly to flower in its first and only season. Leave some plants to set seed if a recurring stand is wanted. Pull spent plants after seeding where spread is not welcome.Pruning
No pruning is needed for this short annual. Leave plants standing to ripen and drop seed for the next year. Remove spent plants after seed set if a tidier look is wanted.✓ Toxicity
Non-toxicPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Direct Sow Timing
Fall or early spring
Days to Maturity
60–90 days
Plant Spacing
6 inches