Physalis philadelphica (synonym Physalis ixocarpa). 70 days.
From Adaptive Seeds:
This is our effort to breed a medium-sized purple tomatillo that stores for a very long time off the vine. Shades range from a slight purple blush on green, to deep purple all through the fruit. Purple tomatillos have a more complex flavor than green ones. They are reputed to keep well already and we are trying to improve on this. A landrace is a variety that has been purposely maintained as a diverse gene pool to help it be more adaptive to harsh conditions. We like this old form of plant breeding, and are using it to create a modern landrace. Always have more than one tomatillo plant in your garden, as they are usually self-sterile.

Packs of 12 seeds
 
Physalis spp. These tasty summer treats are even more mineral-dense than tomatoes, packed with unique phytochemicals and flavonoids.

Days to maturity are calculated from date of transplant.
 
Direct Sowing
• Not recommended

Transplanting
• Sow seeds in trays 6-8 weeks before anticipated transplant date; transplant into 3-4 inch pots when the first set of true leaves appears
• Strong light and cooler temperatures (60-70°F) prevent plants from getting leggy
• Fertilize with Grow every 10-14 days
• When transplanting work in compost, 1/2 cup of Complete Organic Fertilizer, and a handful of bone meal
• Can be buried up to the top 2 sets of leaves
• Use Kozy-Coats or Victorian Bell Cloches to protect young plants