giganteum, reported to 30 m (100 ft) tall. For instance Rhodora (Linnaeus 1763) for Rhododendron canadense, Vireya (Blume 1826) and Hymenanthes (Blume 1826) for Rhododendron metternichii, now R. degronianum. See Thursday Next series, and Shades of Grey. R. ponticum is difficult to eradicate, as its roots can make new shoots. It is the national flower of Nepal, the state flower of Washington and West Virginia in the United States, the provincial flower of Jiangxi in China and the state tree of Sikkim and Uttarakhand in India. While it is a bush, Rhododendron bushes can grow up to 80 feet tall! and R. maximum).  The centres of diversity are in the Himalayas and Malaysia, with the greatest species diversity in the Sino-Himalayan region, Southwest China and northern Burma, from Himachal Pradesh, Uttarakhand, Nepal, Sikkim, Nagaland to northwestern Yunnan and western Sichuan and southeastern Tibet. They may be either evergreen or deciduous. Space plants 2 to 6 feet apart, depending on their estimated mature size. Cullen of the Edinburgh group, placing more emphasis on the lepidote characteristics of the leaves, united all of the lepidote species into subgenus Rhododendron, including four of Sleumer's subgenera (Rhododendron, Pseudoazalea, Pseudorhodorastrum, Rhodorastrum).  Azaleas are frequently used around foundations and occasionally as hedges, and many larger-leafed rhododendrons lend themselves well to more informal plantings and woodland gardens, or as specimen plants. Click to see full answer Beside this, how big do rhododendrons get? Rhododendrons (Rhododendron spp.) Rhododendron niveum is the state tree of Sikkim in India. , Rhododendron are characterised by having inflorescences with scarious (dry) perulae, a chromosome number of x=13, fruit that has a septicidal capsule, an ovary that is superior (or nearly so), stamens that have no appendages, and agglutinate (clumped) pollen.  Most of the Balfourian series are represented by Sleumer as subsections, though some appear as sections or even subgenera. Azaleas make up two subgenera of Rhododendron. Everything you need to know about choosing the right rhododendron for you. Remember, though, that many rhododendrons can grow from 20 to 30 feet tall, weaving a root system that spreads wider than the top growth, so moving smaller azaleas might be more successful.  Bentham and Hooker used a similar scheme, but called the divisions "Series". Rhododendron ponticum has become invasive in Ireland and the United Kingdom. :53 The juice of rhododendron flower is used to make a squash called burans (named after the flower) in the hilly regions of Uttarakhand. You can also take stem cuttings from existing rhododendrons and plant them to grow a new plant. These often-broadleaf evergreen plants boast large clusters of showy blooms at their growing tips in spring. Genus of flowering plants in the heath family Ericaceae, International Code of Botanical Nomenclature, List of Lepidoptera that feed on rhododendrons, List of Award of Garden Merit rhododendrons, List of Sections in Subgenus Rhododendron, "Sorting out the Genus Rhododendron: A Taxonomic Overview of this Large Complex of Species", "GROPING FOR GROUPING: Rhododendron Taxonomy", "The History of Vireya Rhododendron Culture", "Economic history: Farm-gardening and market gardening", "Infrageneric and Sectional Relationships in the Genus Rhododendron (Ericaceae) Inferred from ITS Sequence Data", "Excerpts from and comments on a paper published by: Loretta Goetsch, Andrew Eckert and Benjamin Hall, University of Washington", "Concerning the Origin and Distribution of Rhododendrons", "Dramatic rescue of couple trapped in rhododendron forest", "Maintaining Healthy Rhododendrons and Azaleas in the Landscape", "India has a 'wine country'? Most rhododendron flowers are bell-shaped and have 10 stamens.  It is an introduced species, spreading in woodland areas and replacing the natural understory. In all, Hymenanthes increased from one to two sections, while Azaleastrum, by losing one section and gaining two increased from two to three sections. Most species have brightly colored flowers which bloom from late winter through to early summer.. Then look no further than the hardy rhododendron. Many in this group flower early, such as Little Lou (Rhododendron 'Little Lou'), with yellow flowers and hardiness to USDA zone 6, or Cliff Garland (Rhododendron 'Cliff Garland'), which bears pink flowers and is hardy down to USDA zone 5. , Some species of rhododendron are poisonous to grazing animals because of a toxin called grayanotoxin in their pollen and nectar. ), Subsequent research has supported the revision by Goetsch, although has largely concentrated on further defining the phylogeny within the subdivisions. A small number, however, possess excellent cold hardiness and grow well in Iowa. They are one of the most under rated rhododendron plants available for sale. The truth is they need some light to do well. A number of insects either target rhododendrons or will opportunistically attack them. Information on Rhododendrons by Marc Colombel, founder of the Société Bretonne du Rhododendron. These giants include varieties like Caractacus (Rhododendron Caractacus), hardy down to USDA zone 4 and bearing rosy red blooms, according to the American Rhododendron Society, or the purple-flowered Whidbey Island (Rhododendron 'Whidbey Island') hardy down to USDA zone 6. Growing them is easy, here's how. Soil preparation is best accomplished in autumn before planting the rhododendron in spring. They are native to tropical and temperate regions. Get involved. How to choose the substrate for growing in pots. (2008) shown in (parenthetical italics). Our Lavender Rhododendrons are shipped in large 1 and 3-gallon containers, ensuring you receive an established, better-developed plant.  Xiong et al. Terminology from the Sleumer (1949) system is frequently found in older literature, with five subgenera and is as follows; In the later traditional classification, attributed to Chamberlain (1996), and as used by horticulturalists and the American Rhododendron Society, Rhododendron has eight subgenera based on morphology, namely the presence of scales (lepidote), deciduousness of leaves, and the floral and vegetative branching patterns, after Sleumer (1980). , In Daphne Du Maurier's novel Rebecca, the character of Rebecca is associated with "blood red" rhododendrons throughout the novel, perhaps due to the toxic roots of the plant mirroring the poisonous character of Rebecca. 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