Hosta nigrescens

Hosta nigrescens (F. Maekawa 1937/AHS 1993)

Hosta 'Tenryu'

Subgenus Schmid Giboshi Zonneveld  
Section Schmid Helipteroides Zonneveld  
Hosta Library species file Hosta nigrescens
Origin Japan, northern Honshu.  See Map.
Habitat Only known as a cultivated plant in gardens, the occurrence in the wild is subject to further field investigations
Japanese name Kuro Giboshi = black hosta
Plant 60–70 cm diameter, 65 cm high (24–28 x 26"). Sprout cataphylls pruinose, blackish grey.
Leaf Petiole 30–50 cm (12–20"), slightly arching but erect, forming a tall plant, gray pruinose glaucous, green background.
Leaf 25-30 x 17.5–22.5 cm (10–12 x 7–9"), leaf attitude at petiole angled at joint then ±arcuate spreading, ovate-cordate, transition usually tight and contracted, acuminate tip, rugose in part, ±keeled, no waves in margin; entire plant very pruinose initially, farinose, gray green initially, leaf underside and petioles whitish, leaf upper surface pruinose grayish green, slowly changing to shiny deep green.
11–14 pairs of veins, sunken above, very projected, strigose below.
Inflorescense Scape far exceeding height of plant, to 140 cm (56"), measured to 180 (200) cm (72 (79)") on mature plants, with ±3 (5) sterile bracts, very straight, erect, upper part rarely, but occasionally bending, solid, terete, permanently pruinose, lasting until dehiscence; bracts flat and broad, thick and fleshy, green or whitish green, developing and opening in a stellar form as seen from above.
Raceme 30 cm (12"), 15–25 flowers, widely spaced.
Flowers 5 cm long, 3 cm broad (2 x 1.25"), mostly white to white, suffused with very light purple, and barely darker stripes; perianth expanding, funnel-shaped, in the central part dilated, bell-shaped, lobes spreading straightly to ±angled to the axis of perianth, stamens not very superior, equal or slightly shorter than perianth.  
Anthers purple anterior and posterior, lighter posterior, approaching bi-color, looks light purple.
Blooming Time July/August
Fertility Very low pod fertility (almost sterile), low pollen fertility
Growing conditions  
Suitable for containers  
Special remarks Very likely most plants present in western collections and gardens are related to H. 'Tenryu' rather than to H. nigrescens
In Hosta Mill Collection Not the real wild species, but a plant from a strain that has been in cultivation for centuries is present (this may account for the low fertility) and H. 'Tenryu', which is considered to be identical by W.G. Schmid.
  • H. 'Tenryu' is considered a named clone.
  • H. 'Ogon Kuro' = H. nigrescens 'Aurea' = Ogon Kuro Giboshi : an all yellow form.
  • H. 'Tenryu Nishiki': form with an irregular streaky yellow-white margin.
  • H. 'Allegan Emperor' (H. Deshane/K. Herrema/P. Ruh 2000) = (unknown) x H. nigrescens
  • H. 'Allegheny River' (Alex Malloy 2005) = H. 'Tenryu' seedling
  • H. 'John Wargo' (Henry W. Weissenberger 1986) = H. nigrescens seedling
  • H. 'Krossa Regal' (A. Krossa 1980) = Chodai Giniro Giboshi, a Japanese hybrid, parent of some highly valued variegated sports.
  • H. 'Flower Power' (K. Vaughn 1987) = H. nigrescens x H. plantaginea
  • H. 'Garnet Prince' (Pauline Banyai/Jim Dishon 1991) = H. nigrescens hybrid
  • H. 'Green Wedge' (P. Aden 1976) = H. nigrescens x Hybrid (unknown)
  • H. 'Nate the Great' (R. Solberg 2003) = H. nigrescens x H. 'Tokudama Aureonebulosa'
  • H. 'Smokerise Frosted Vase' (E. Lunsford Jr. 1994) = H. 'Frances Williams' x H. nigrescens