The "Red" Horse Chestnut is a (tetraploid?) cross between the shrubby Red Buckeye or Firecracker, Aesculus pavia of the mid-west USA and the Common Horse Chestnut, Aesculus hippocastanum, of South Eastern Europe. The hybrid appears to have been around since early Victorian times, possibly arising in Germany by 1820.
It is a generally "desired" tree although Alan Mitchell, writing in the 1970s, disparages it greatly, as dark and uninteresting, but thankfully short-lived! Does not get much Horse Chestnut Leaf Miner, which is a relief. A bit less troubled by diseases than A. hippocastanum, but does seem to have physiological bark breakdown problems and to get bleeding canker a lot, limiting its life span.
There are three red horse chestnut trees at the front of Hadlow college, one by the road and two by the river. They vary slightly in the hue or "redness" of the flowers, but whether one or more is actually "Briotii" is a guess well above my pay grade - but I think NOT.
Could this one be 'Briotii'?
According to the RHS Dictionary, the tree is "low-domed" but this must be relative. The bark is said to turn from dull green tinged pink, becoming red-brown and rough with distinct lenticels. The branches are said to be twisted and spreading, with drooping tips.
The buds are terminal, often in pairs. They are up to 2.5 cm long, ovoid and slightly resinous.
There are 5 - 7 leaflets per leaf, each sub-sessile, obovate up to 25 cm long, actually broader than in A. hippocastanum (?), wrinkled, dark green above, lighter green beneath, double crenate, the leaf with a petiole of maybe 23 cm. The leaves should often be recurved and twisted. Midrib is red at its origin?
The flowers form panicles 20 x 10 cm. The flower corolla is up to 1 cm in length, the petals rose-pink, their centres blotched yellow initially, then the centre turning cerise as the flower is pollinated. The petal margins should be glandular - which I have never noticed before! Stamens protrude slightly, but nothing like as far as in A. hippocastanum.
The spiny fruit is spherical and up to 4 cm diameter. There are 1 - 3 small seeds or "conkers".
'Aureo-marginata' Leaves edged with yellow.
'Briotii', perhaps called the Ruby Horse Chestnut, has a larger inflorescence, with much darker red petals, with a glabrous pistil. The fruit is only laxly spined. Notably dark green foliage. Red "midrib" - (must be petiole)? The cultivar was named in 1858 to honor Pierre Louis Briot (1804-1888), the chief horticulturist of the State gardens at Trianon-Versailles near Paris,
'Foliis Marginatis'
A variegated form with a dark green border to the leaf, then an irregular band of yellow, the centre being pale green
'Fort McNair' (named from where it was selected) has dark pink flowers with yellow throats and resists leaf scorch and leaf blotch. It has a more 'pavia' type leaf.
'O'Neil', or 'O'Neill Red' produces larger (10–12 inch) panicles with brighter red flowers. Introduced by Monrovia nursery in about 1979 (Jacobson,1996). Monrovia spells the cultivar name as O'Neill; many variations of this name are found in nursery catalogs and horticultural publications.
'Plantierensis' is a back-cross to A. hippocastanum. There are usually 7 sessile leaflets, uneven with ribbed blades. The inflorescence is very like A. hippocastanum but a delicate pale pink. The fruit is prickly but undeveloped, as it is triploid, so you don't get conkers. The origin of this cultivar is the nursery of Simon-Louis Frères, Metz, France, 1894.
'Theo Jansen'.
See list at Pavia Nurseries, Holland, a leading supplier of Aesculus plants in western Europe.
There are some very nice Aesculus at the Almshouses, Faversham, including this very pretty Aesculus x carnea.
No comments:
Post a Comment