Greek helios—sun, referring to the diurnal flowers.
Plants in nature epiphytic or growing on rocks. Stems erect, scrambling or pendulous. Ribs with 3-7 pointed ridges, rarely flat. Areoles with short or bristle-like spines. Flowers diurnal, funnel-shaped, open for several days, mostly red. Flower tube with scales and areoles with bristly spines. Fruit spherical or ovoid, fleshy.
Grown in collections as H. speciosus (Cav.) Britton & Rose which has reddish purple flowers except for var. amecamensis (Heese) Weingart which has white flowers. H. cinnabarinus (Eichler) Britt. & Rose from Guatemala has half-closed red flowers with yellow throats.
Stems generally with 3-5 ridges, wings or ribs.
3 or more species likely to be merged with Aporocactus or, more likely, Disocactus.
Source: (1997). Cactaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.
