Haworthia rigida
Haworthia It distinguishes for the leaves that are longer with a stiff truncate end-area.
Habit: It is a stemless solitary to slowly proliferous evergreen leaf-succulent species.
Blooming season: Autumn.
Cultivation and Propagation: Haworthia rigidas are of easy cultivation and relatively low maintenance, which makes them a good houseplant, and can be excellent subjects for the beginning succulentophile (they can grow easily on window sills, verandas and in miniature succulent gardens where they are happy to share their habitat with other smaller succulent plants, or in outdoor rockeries). For best results, use a shallow pot.
Exposition: The plant needs light shade to shade, but will take full sun part of the day. (with some sun exposure the leaf develops a nice reddish tint and remains compact)
Watering: During the hot summer months, the soil should be kept moist but not overly wet. During the winter months, water only when the soil becomes completely dry. Wet soil quickly causes root and stem rot, especially during chilly winter months. No water should ever be allowed to stand around the roots. Low ambient humidity is always needed.
Hardiness: Although the plant will survive mild frost if kept dry (hardy as low as -5° C) it should be protected from severe cold and prolonged frost conditions.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz