SAVANNAH FALSE PIMPERNEL
Also Known As
This pretty little native wetland groundcover forms mats usually no taller than six inches. The outstanding feature is the showy, albeit small, violet-blue and white flowers. This species is a nectar source for small pollinators and is a host plant for the White Peacock butterfly. I have found no mention of any edible or medicinal uses for this particular species.
COMPARE WITH Torenia crustacea, a common non-native that is very similar in appearance. CAUTION: Although I have found no warnings concerning this exact species, I thought that I would mention that another within the genus is a listed emetic. Lindernia diffusa is is used in Brazilian traditional medicine as an emetic, where it is known as Caa-ataya. CONSERVATION STATUS: It is "Critically Imperiled" in south Florida according to Regional Conservation.
NOTE: I have found no edible or medicinal uses listed for this particular species to date. Please let me know if you find any. Thanks.
RELATED SPECIES WITH MEDICINAL USES: Two related Asian species are used medicinally. Lindernia antipoda is used medicinally in Indonesia. Also, Lindernia ciliata is used medicinally in its native China and Taiwan.
IN THE GARDEN:
- GROUNDCOVER: "It thrives in the moist boggy soil at the edge of a pond."  SMG Growers writes, "Useful as a flat groundcover between stepping stones or to surround rocks or steps in the landscape." 2]
- CONTAINERS: Good for spilling out of containers and in hanging baskets." 
- ROCKERY: "A good rockery plant. 
- WATER GARDENS: Suncoast Tropicals tell us that it may be grown in shallow water. 
WILDLIFE: The flowers attract small pollinators.  It may be a host for the White Peacock butterfly, as Lindernia is in Costa Rica. 
NATIVE TO: Florida, most counties, except some of the farthest west panhandle counties.
HABITAT: Freshwater wetlands.  Pinelands, marshes, swamps. 
DESCRIPTION: A small, 2 to 3 inch tall, evergreen, perennial. Plant Delights Nursery claims that it is deciduous [they are located in North Carolina]. Width: Spreading, 18 to 24" or more wide. 
- STEMS: Weak.
- LEAVES: To half an inch wide, opposite, sessile, delicate, succulent, light green, heart shaped.
- FLOWERS: Small, white or very light lavender, spotted with blue-violet. It blooms year-round during warm winters. It is reported to flower from Spring through Summer.  Three "united petals, and two smaller ones, joined tube is violet." 
- HARDINESS: Usda zones 6A to 9B according to garden.org. Here in Florida, I have often observed it in zone 10B as well. Hardy down to 0F.  Plant Delights reports hardiness at their North Carolina nursery down to 0F. 
- PROPAGATION: By cuttings. 
ETYMOLOGY: Grandiflora refers to the large flowers [for the genus].
NOTE: Some websites mistakenly list it as a member of the Figwort family, Scrophulariaceae.
SIMILAR SPECIES: Here in Florida, there are two other species of Lindernia found in the wild, they are also natives. Lindernia dubia, MOISTBANK PIMPERNEL, aka YELLOWSEED FALSE PIMPERNEL, is even more widespread and has flowers that are lighter colored, almost appearing white at times. Lindernia monticola, PIEDMONT FALSE PIMPERNEL, which grows in Flagler County and four nearby counties. Roger Hammer writes, “The naturalized Lindernia crustacea differs by having a purple line across the lower lip.” 
Sources for acquiring
I know of no native plant nurseries that propagate this plant. It is easily found in the wild, in wet places, so try transplanting some. Remember to keep the soil moist.
 Atlas of Florida Vascular Plants
 SMG Growers
 Plant Delights Nursery
 Suncoast Tropicals
 Field Identification Guide to Plants Used in the Wetland Assessment Procedure, 2008, Denton and Willis
 Plants from the Brazilian Traditional Medicine: species from the books of the Polish physician Piotr Czerniewicz(Pedro Luiz NapoleãoChernoviz, 1812–1881)
 Useful Tropical Plants
 Butterflies, Moths, and Other Invertebrates of Costa Rica: A Field Guide
 Everglades Wildflowers, by Roger Hammer
 Pollinator Friendly Gardening: Gardening for Bees, etc.
 Hawthorne Hill Wildflowers
 Regional Conservation