Aesculus parviflora Walter (U.S.A.) – A very rare escape from (or perhaps often more likely, a relic of) cultivation, probably locally naturalizing. First observed in deciduous woodland in Peer in 2013. In 2017 also discovered on the verge of Berlarebroek nature reserve in Berlare and subsequently confirmed. There, it grows in damp woodland and it was reported to sucker and create colonies. Aesculus parviflora is also known to reproduce from seed in the Botanic Garden of Meise. A dozen several years old seedlings were found in woodland, nearly 200 m from the nearest planted individuals (Ronse 2011).
This species of Aesculus is shrub-like, much unlike the more widely planted trees such as A. hippocastanum and A. carnea. Among the species encountered in the wild in Belgium confusion is only likely with A. pavia (see the key for differences).
Aesculus parviflora is, although widely planted, only exceptionally seen as an escape. It was reported from the British Isles as an extensively suckering relic of cultivation (Clement & Foster 1994) and from Hungary where it was classified an ephemeral escape (Botond & Zoltán 2004).
Selected literature:
Botond M. & Zoltán B.D. (2004) Biological Invasions in Hungary. Invasive Plants. Természet BUVAR Alapítvány Kiadó.
Clark R. (1982) Bottlebrush buckeye: mysteries of a southern delight. Morton Arbor. Quart. 18(1): 1-5.
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Pohl K. (1971) Über die Strauchkastanie Aesculus parviflora. Palmengarten 35(2): 64.
Ronse A. (2011) 'Botanic garden escapes' from the living collections at the Botanic Garden. In: Hoste I. (ed.), The spontaneous flora of the National Botanic Garden of Belgium. Scripta Botanica Belgica 47: 219 p. [available online at: https://www.researchgate.net/publication/289897146_Botanic_garden_escape...