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Overview
Lithotoma is a small genus of herbs in the bellflower family, Campanulaceae (subfamily Lobelioideae), native to Australia, and closely related to and sometimes merged with Isotoma. Plants are low, tufted to erect annuals or short-lived perennials 4-16 inches (10-40 cm) tall, with narrow, toothed or lobed leaves and milky sap. From spring into summer, slender stalks carry star-shaped flowers with five narrow, pointed lobes, in white, pale blue, or violet, each up to about 1 inch (2.5 cm) across. The genus grows in seasonally moist, open sites such as rock crevices, granite outcrops, streamsides, and disturbed ground, in full sun to light shade. The milky sap contains irritant alkaloids that can inflame skin and eyes on contact. Plants are adapted to a wet growing season followed by a dry rest, and many behave as annuals, completing their cycle from seed in a single season. Free-draining soil and seasonal moisture suit them, while heavy, wet, or shaded conditions reduce flowering.
Native Range
Lithotoma species are native to Australia, where they grow in seasonally moist habitats including granite outcrops, rock crevices, creek margins, and open disturbed ground across southern and eastern regions.Suggested Uses
Grown in rock gardens, gravel gardens, seasonal container displays, and as warm-season annuals in beds and pots. Native-plant gardens in Australia use the species in outcrop and dry-streambed plantings where seasonal moisture collects.How to Identify
Appearance
Size & Dimensions
Height4" - 1'4"
Width/Spread4" - 1'
Bloom Information
Flowering occurs mainly from spring into summer, generally September to January in the native Southern Hemisphere range, following seasonal rains. Star-shaped flowers open on slender stalks over several weeks. Small capsules follow and release the tiny seed as they dry.
Detailed Descriptions
Flower Description
White, blue, or violetFoliage Description
GreenGrowing Conditions
Sun Requirements
Requires 6-10 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
Care & Maintenance
Care Guide
Lithotoma grows in full sun to light shade in free-draining, sandy or gravelly soil with moisture through the growing season. Plants follow a pattern of active wet-season growth and a drier rest, and many are grown as annuals from seed. Even moisture during growth and flowering supports the display, while heavy, waterlogged, or deeply shaded soil reduces it. The milky sap is a skin and eye irritant. Most species suit mild-temperate to warm climates and are frost-sensitive, grown as warm-season annuals where winters are cold.Pruning
Spent flower stalks are trimmed to prolong flowering and limit excess self-seeding. Annual plants are cleared once they finish and set seed. Cutting back is done after flowering to tidy perennial species, and the cut stems release irritant sap.Container Growing
Suitable for container growing
Minimum container size: 1 gallons