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Information Panels : Evergreen Rhododendrons

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Author: Ing. Uljana Blažková


Basic Setup of Rhododendron Collection

Most of the collection was planted in 1994 from pre-grown plants held in stock garden. Later a sample of Czech rhododendrons breeding and other species of plants from Ericaceaea family were added and continually new specimens were planted in related groups. The collection is focused on wild species in botanical system used in seventies of last century, which is based on a bud position and character of hair on underside of leaves. The collection also pays attention to a geographical origin within the botanical groups. There are 4 types of hair on the bottom side of rhododendron foliage: simple pile (pile), glandular pile (glandule), scaled pile (scale) and bifurcated pile (flock). According to this, rhododendrons are divided into 3 groups:

1.  Lepidotae
This group has mostly scaled piles. Some species have scales and simple piles, too. They are evergreen species with mostly small leaves, but semi-deciduous and deciduous plants can be found here as well.

2. Vilosae
Species in this group have mostly piles but also glandules. They are deciduous to semi-deciduous, only very rarely evergreen. They are commonly called azaleas.

3. Floccaceae
Here are all evergreen species with large flowers and leaves with flocks on the underside of foliage, sometimes with glandules.

Generally, this division is elementary for today’s botanical system, which divides plants into species, sub-genera, sections and sub-sections. But it is always adjusted according to progress in molecular genetics.


Evergreen Rhododendrons in Chotobuz

Botanical rhododendrons in each group are complemented with a sample of cultivars, but it is just a fraction of all worldwide breeding (several tens of thousands). Groups are placed in landscape to fulfill the best their ecological requirements.

Sub-genus Rhododendron

Characteristics: species belonging to Lepidotae group have mostly small evergreen foliage, they reach from 10cm to 2m (in local conditions), need protected shady stand with sufficient humidity. But also semi-deciduous and deciduous species belong here. There are two display beds of species in this group. They are often hybrids, not pure botanicals, because they come from seeds from botanic gardens where they pollinate freely with related species. Rhododendrons are very easy to cross and where are more related plants together as in the gardens or sometimes in nature; seeds are most of the time of hybrids.

In first display there are two European species: rusty-leaved alpenrose (R. ferrugineum) which name is from rusty colored bottom side of leaves, and hairy alpenrose (R. hirsutum) named after significant hair on edges of leaves. From American species is here Carolina Azalea (R. minus, syn. R. carolinianum). And from Asia are here to be seen: R. concinnum – tender one with very decorative crimson flowers, R. micranthum resembles of Czech native Wild Rosemary or Marsh Labrador Tea (Ledum palustre) and R. impeditum which is a low shrub with purple flowers and it is an ancestor to many cultivars, here represented by ´Moerheim´

Second display bed shows early blooming rhododendrons from Far-East. They are e.g. Korean Rhododendron (R. mucronulatum) and Chinese Alprose (R. dauricum) which is semi-deciduous to deciduous. Loosing its leaves depends on a stand – when on sheltered one, the foliage survive in winter. Other specimens include R. dauricum subsp. Ledebourii (less deciduous) and very decorative R. x  praecox which is a cross between R. dauricum a R. ciliatum hybridized by Isaac Davis in the middle of 19th century in England. And the last one is Kamchatka Rhododendron (R. camtschaticum) – the only one from sub-genus Therorhodion.



Translation: Marketa Machackova