'Fastuosum Flore Pleno'
Double Rhododendron
"Where the mountain river flows
And the rhododendron grows
Is the land of all the lands
That I touch with tender hands."
-Louise McNeill
(1911-1993)
(1911-1993)
'Fastuosum Flore Pleno' is an unusual hybrid of Rhododendron ponticum & R. catawbiense, with each trumpet in the truss being a double or semi-double, looking like a flower inside a flower. The inner flower has something of the look of a crumpled tissue flower.
Its buds are large & colorful by late April (as shown in the first photo) & it fully flowers in May (second photo). Each truss can have a dozen or more trumpets. The color is lavender with a large greenish-yellow to brownish-gold flame on the dorsal petals of both the inner & outer trumpets. It is a sterile hybrid propagated from cuttings & grafts.
It likes to be in sun or bright shade, in moist well-draining organically rich acidic soil. It grows to six feet in ten years, but can eventually double that height.Of its parents, R. catawbiense or Mountain Rosebay is the primary source of the classic Ironclads or standard large-leafed scaleless (Elepidote) evergreen rhodies, hardy & reliable. The original species is native to the American south, & was first described 1809 by Scottish botanist John Fraser (1750-1811). The species name is after the Catawba Indians who had medicinal uses for the shrub, & for Catawba River in North Carolina, where Fraser first encountered it.
R. catawbiense is of the same subgenus as R. ponticum so they crossbreed very easily though originating on different continents. It is the source of some of the best blues & purples in Ironclad rhododendrons. The species is native to the Pontus region of the Black Sea. It is so adaptable that after it was introduced into England, it became a pest-plant spreading through forest edges displacing native shrubs. Hybrids aren't invasive but they certainly are hardy. The species is the most toxic of all rhododendrons & in the Pontus where bees are adapted to its toxins, honey made from the Pontus rhododendron becomes an intoxicant known as "Mad Honey."
'Fastuosum Flore Pleno' is an heirloom shrub bred before 1846 by Geber Francoisi of the Francoisi Brothers nursery in Ghent, Holland. It's a 1993 recipient of the Award of Garden Merit.
It has never wavered in popularity because there are extremely few varieties of double-flowered eleplidote evergreen rhododendrons. Being sterile, it has not been possible to use it to pass its double-flower trait to other cultivars.