Nematanthus is a genus of flowering plants in the family Gesneriaceae. All of its species are endemic to Brazil.[1] Compared to other gesneriads, Nematanthus has leaves that are small, succulent, and hard-surfaced. The plant has a trailing, branching, and spreading habit; it is generally an epiphyte in nature and a hanging-basket plant in cultivation. The flower has fused petals. In some species, the flower has a "pouch" at the bottom. The fancied resemblance of such flowers to a goldfish gives these plants the common name goldfish plant or guppy plant.
Hummingbirds will often feed from the nectar-filled "goldfish" flowers.
Nematanthus species are perennials or subshrubs, typically growing epiphytically, less often in humus-filled pockets on rocks. Their leaves are often reddish underneath. Their flowers have fused petals and vary quite widely in shape. Some have flowers with a "pouch" on the lower surface of the flower and a small opening (particularly those commonly cultivated). Others have flowers that are twisted through 180° when fully open (resupinate), so that if pouched, the pouch is at the top. Resupinate flowers may be brightly coloured, funnel-shaped and compressed from side to side, or white and bell-shaped. Some species have flowers that are borne on long pedicels and hang down below the plant, others have short pedicels so that the flowers are close to the stem.[2][3]
The genus Nematanthus was first described by Heinrich Adolph Schrader in 1821,[4] with the only species (and so the type species) being Nematanthus corticola,[5] one of the species with flowers hanging down on long pedicels.[3] The name Nematanthus is from Ancient Greek nema meaning 'thread' and anthos meaning 'flower', referring to the 20 cm (8 in) long pedicels of the type species.[3]
Nematanthus is placed in the subfamily Gesnerioideae, tribe Gesnerieae, subtribe Columneinae.[6] Within the subtribe, it forms a clade with Codonanthe, Codonanthopsis and Lesia:[7][8]
Lesia
Codonanthopsis
Codanthe
Nematanthus
As of April 2021, Plants of the World Online accepted the following species:[1]
N. crassifolius
N. fissus
N. fritschii
N. gregarius
N. strigillosus
N. wettsteinii
Nematanthus thrive at temperatures between 18 and 25 °C (64 and 77 °F), although they stay more compact if grown at 15 to 17 °C (59 to 63 °F).[9] They may lose their leaves if temperatures go above this level.[9][10] Nematanthus gregarius is said to tolerate temperatures down to −1 to 2 °C (30 to 35 °F).[11] Nematanthus do best in bright indirect light,[9] and can easily burn in direct sunlight. They prefer high humidity, and grow better under these conditions, but adapt to household humidity.[10][12] The tuberous roots of this plant retain water, and Nematanthus prefer the soil to remain moist, and well-drained. The goldfish plant enjoys being pot-bound, and is more likely to bloom in that state. When grown in the right conditions, Nematanthus is known to bloom year-round. To encourage new blooms, regular pruning of the plant is recommended.[13] Plants can be propagated from cuttings.[9]
'Tropicana' originated from a cross made in the United States by W. R. Saylor. The parents were reported to be N. perianthomegus and N. gregarius.[9] As of April 2021, N. perianthomegus was treated as a synonym of N. hirtellus by Plants of the World Online,[14] although other sources say that it is a synonym of N. tessmannii.[3] 'Tropicana' is initially upright, after which older branches trail. The leaves are 5 by 2.5 cm (2.0 by 1.0 in), glossy dark green with a reddish brown margin on the under surface. The flower has a red-brown calyx, the fused petals (perianth) being yellow with red-brown stripes and spots. 'Tropicana' produces flower buds all year round.[9]
'Rio' also originated from a cross by Saylor, in this case between N. gregarius and N. fissus (syn. Hypocyrta selloana). Its leaves are slightly larger than those of 'Tropicana', 6 by 6 cm (2.4 by 2.4 in), lighter green on both sides and less glossy. The flower is smaller, with a light green calyx and a striking orange-red perianth. 'Rio' makes buds all year round.[9]
'Herens' is of unknown origin. It resembles 'Tropicana', with a somewhat smaller leaf, 4.5 by 2 cm (1.8 by 0.8 in), with a reddish tinge on the underside. The calyx is red-green and the perianth orange-red. It can flower abundantly all year round.[9]
'Gietvoz' is also of unknown origin. It is a compact cultivar, less sensitive to unfavorable growing conditions such as overwatering or bright light. The leaf is smaller, 3.5 by 2 cm (1.4 by 0.8 in), and less tapered than that of other cultivars, and is thick, waxy and glossy. The underside of the leaf is red with a green edge and is clearly visible as the leaves are somewhat upright. The flower has an inconspicuous light green calyx and an orange-yellow perianth. Although 'Gietvoz' does not flower as readily as other cultivars, it has a good growth habit and attractive foliage.[9]
Saylor also made crosses between Codonanthe gracilis and Nematanthus hybrids, creating the hybrid genus × Codonatanthus. Two of the resulting cultivars are 'Fiesta' and 'Aurora'.[15][9]
Nematanthus gregarius 'Dibley's Gold' has variegated leaves.[10]
Nematanthus is considered non-toxic and safe for pets by the ASPCA.[16]
Nematanthus is a genus of flowering plants in the family Gesneriaceae. All of its species are endemic to Brazil. Compared to other gesneriads, Nematanthus has leaves that are small, succulent, and hard-surfaced. The plant has a trailing, branching, and spreading habit; it is generally an epiphyte in nature and a hanging-basket plant in cultivation. The flower has fused petals. In some species, the flower has a "pouch" at the bottom. The fancied resemblance of such flowers to a goldfish gives these plants the common name goldfish plant or guppy plant.
Hummingbirds will often feed from the nectar-filled "goldfish" flowers.
