Ostrya chisosensis
Sponsor
Kindly sponsored by
Claire Mansel Lewis
Credits
Owen Johnson (2022)
Recommended citation
Johnson, O. (2022), 'Ostrya chisosensis' from the website Trees and Shrubs Online (treesandshrubsonline.
Genus
Common Names
- Chisos Hop-hornbeam
- Big Bend Hop-hornbeam
Synonyms
- Ostrya knowltonii subsp. chisosensis (Correll) E. Murray
- Ostrya virginiana var. chisosensis (Correll) Henrickson
A small tree to 12 m, with an open, narrow crown. Bark soon ridged and scaly. Twigs sparsely to moderately pubescent, the hairs never glandular. Leaf small and quite narrow (35–50 × 20–30 mm), elliptic to lanceolate, with few (5–12) pairs of lateral veins; pubescent only under the veins; margin finely double-serrate; petiole 3–6 mm long, with sparse hairs (never glandular) or with none. Male catkins short (3–4 cm); fruiting catkin short (2–4 cm); bladders 10–18 mm long. (Furlow 1997).
Distribution Mexico Coahuila (Sierra Madera del Carmen) United States Texas (Big Bend National Park)
Habitat Canyons, 1500–2300 m asl, by streams and on moist slopes.
USDA Hardiness Zone 6
RHS Hardiness Rating H5
Conservation status Critically endangered (CR)
Ostrya chisosensis was first differentiated by Donovan Correll in 1965 from O. knowltonii, a better-known species which inhabits different canyons within the same region of North America. Both have adapted to the harsh and sometimes dry local conditions by growing as small trees with smaller and fewer-veined leaves than in the rest of the genus; O. chisosensis has narrower leaves than O. knowltonii and it never bears gland-tipped hairs (Powell 2010). Some authorities, including Plants of the World Online (Plants of the World Online 2022) treat the two species as synonymous, but recent genetic sequencing suggests that the closest relative to O. chisosensis may be the Chinese O. rehderiana (Li et al. 2019). Within the United States, O. chisosensis is known only from Chisos Canyon in the Big Bend National Park in Texas; just across the border in Mexico’s Sierra Madera del Carmen, a further population may intergrade with plants currently treated as O. virginiana (Poole, Carr & Price 2007; McCauley & Paces 2015).
In 2015, Ostrya chisosensis was represented in America in three ex-situ collections (Beech, Shaw & Jones 2015). It is probably not a plant adapted to grow in north-west Europe, but may prove successful in warmer regions further south.