Tilia paucicostata Maxim.

Tilia paucicostata, usually a small tree in the wild, has rather small leaves, green beneath, which are perhaps less showy than those of many other Chinese limes. Described by Maximovicz in 1892 from a specimen collected in Gansu by the Russian explorer and Siberian separatist Grigory Potanin, the specific epithet implies ‘few veins’, although 5–6 major leaf veins is not notably few for the smaller-leaved species (Pigott 2012).

This is in several ways a peripheral species. While conventionally placed in Section Anastraea, characterized by a lack of stellate hairs beneath the leaves, its position is uncertain (Pigott 2012). While the widespread subsp. paucicostata lacks these hairs, they are present in subsp. yunnanensis (see taxonomic note above). Furthermore, all subspecies have short filaments (under 3 mm) so the stamens are retained within the corolla. This is useful in identification, clearly distinguishing this species from T. amurensis and T. cordata. Its wild distribution lies at the northwestern fringe of the genus’ distribution in central China, an area with a continental climate and predominantly summer rainfall.

Despite being in cultivation for more than a century, it remains very uncommon, and rarely mentioned in the literature. The example in the lime collection at Dibbins Wood, Deene Park, Northamptonshire, has grown into a notably graceful tree, 14 m, dbh 31 cm by 2009 (Tree Register 2018). Larger examples grow in the lime avenue at Thorp Perrow in North Yorkshire (22 m, dbh 47 cm in 2014) and at the Glasnevin National Botanic Garden in Dublin (16 m, dbh 51 cm in 2012). These trees were planted in 1936 and 1914 respectively and are probably grafts from the tree grown at Veitch’s Coombe Wood Nursery from the original seed introduction, made by Ernest Wilson in north west Hubei in 1901, under W 2422 (Sargent 1916; Bean 1981). Specimens in western England may come into growth early, suffering damage from late frosts (Pigott 2012).

In continental Europe, there are young trees at Gothenburg Botanical Garden (2008 accession, wild origin – Gothenburg Botanical Garden 2020) and the Arboretum Wespelaar (1991 accession – Arboretum Wespelaar 2020). Despite a long history of cultivation, it is a rare species in North American collections. A tree planted in 1920 at the Arnold Arboretum was measured at 56 cm dbh in 2019 (Arnold Arboretum 2020). Despite a less than encouraging provenance for such an obscure tree – the Parks Department of Rochester, New York – Pigott (2012) is confident of its identification. There are several young examples from NACPEC collections made in Gansu and Shaanxi at the Morton Arboretum, Illinois (Morton Arboretum 2020).