Ammocharis baumii (Harms) Milne-Redh. & Schweick. was first described as a Crinum but has since been reclassified as an Ammocharis. It is native to Angola, Namibia and South Africa and found only on the margins of seasonally wet depressions in grassland and veld. This species forms solitary, naturally small bulbs, usually less than 2 cm in diameter. Its narrow leaves are 1-2 mm in width and glossy. Ammocharis baumii produces only one flower per bulb, per blooming. This spidery flower is held erect, providing a striking silhouette. The 10 cm wide flower opens white and within 12 hours of opening takes on a decidedly bright pink cast with even the perianth tube turning this cheerful colour. The 5-6 cm long, recurving tepals are u-shaped in cross section (4 mm) The peduncle is short, usually under 2 cm and the perianth tube 10 cm in length.
Despite having been described over a century ago, Ammocharis baumii remains rare in cultivation outside of its native range. Seed is always very scarce and the bulbs take 6+ years to reach blooming size from seed. In habitat the mature bulbs remain dormant during the cool, dry winters and leaves emerge in late spring when rains arrive. In good years mature bulbs can bloom 2-3 times between spring and summer. It is believed that in order to produce good blooms each year, A. baumii requires a totally dry rest in winter, contrasted by a hot summer with full force of full sun and with intermittent watering to wake it from its slumber, followed when in active growth by deep watering every 10-14 days, allowing the potting media to dry out almost completely between waterings.
Uluwehi Knecht has found that Ammocharis baumii grows well outdoors in full sun in Honolulu, Hawai'i where it remains evergreen year-round if it is never allowed to dry out. Under these moist, warm tropical conditions A. baumii is remarkably tolerant of very high humidity (70% rh+) and of high rainfall (3550 mm pa) when grown in 100% coarse horticultural pumice. He hasn't yet bloomed the plants under these conditions (however these plants weren't yet blooming size).
Photos 1-5 by Uluwehi Knecht below show this species flowering in Berkeley, California.
The photos below were taken by Dylan Hannon who grows this plant in a 2" rose pot, mostly in pumice. The plant gets about 5 months of dry winter dormancy.