• Marco Bartolini

hilliers arboretum talk

Notes below from the guided tour and talk given by Marco Bartolini, September 25th 2021.

Koelreuteria paniculata or The Pride of India Tree or Golden Rain Tree. It is a very attractive large headed tree with attractive reddish leaves in spring turning to dark green, then brilliant bright yellow in Autumn. Larger panicles of small yellow flowers in July/August, followed by bronze-pink or red 'bladder' fruits. Native to eastern Asia, in China and Korea. It was introduced in Europe in 1747. Golden rain tree is susceptible to root rot, a disease that initially mimics the symptoms of water stress by causing foliage wilt and branch dieback. As the disease progresses, the bark often darkens and oozes a gummy sap. Life span of approx. 50 years. Trials in Sweden have shown that this tree is hardy to the stresses of urban planting over many other species.

Metasequoia glyptostroboides, or Dawn Redwood, is a fast-growing, endangered deciduous conifer. Growing to 18m in fewer than 50 years, it has developed into the most wonderfully conical tree with fresh green soft foliage, giving rise to the common name. The rusty copper brown bark covers a beautifully fluted trunk. It is the sole living species of the genus Metasequoia and one of only three true redwoods. The other two being giant redwood (Sequoiadendron gigantium) and coastal redwood (Sequoia sempervirens). Metasequoia glyptostroboides is an ancient yet also relatively new tree. Fossil records date back to the Mesozoic era and it was thought to be extinct until a small group were discovered by the Yangtze river, China in 1944. Introduced into UK in 1948/9 and the first tree grown at Cambridge University Botanic Gardens with seeds given to Hiller Gardens. Metasequoia glyptostroboides ‘Emerald Feathers’ is a cultivar of the Sir Harold Hillier Gardens’ and appears as their emblem.

1. Cercidiphyllum japonicum 'Morioka Weeping' Katsura or Candyfloss tree. 'Morioka Weeping' is a deciduous tree with a dome-shaped, weeping habit and may eventually reach a height in excess of 20m but unlikely in UK. The heart-shaped leaves emerge reddish-purple in spring before turning blue-green; in autumn, the leaves turn shades of yellow and orange and may emit a burnt-sugar scent. Originally from Japan and parts of eastern China this tree was introduced to Britain in 1881. It had arrived in America 16 years earlier, collected by Thomas Hogg who was a US customs officer.

2. Liquidambar styraciflua 'Moonbeam' or Golden-leaved Sweet Gum. A mature height of 10 m. It is a small tree with golden-yellow young leaves in spring and early summer, darkening to pale green as they age before showing red, pink and orange tints in autumn. native to warm temperate areas of eastern North America and tropical montane regions of Mexico and Central America. Sweet gum is one of the main valuable forest trees in the south-eastern United States, and is a popular ornamental tree in temperate climates. It was introduced to Britain in 1681.

3. Betula papyrifera 'Vancouver' or Paper Birch. A cultivar of Vancouver, Canada. Betula papyrifera is a short-lived species of birch native to northern North America. It was introduced into the UK in 1750. Paper Birch has dark green foliage throughout the season. The pointy leaves turn an outstanding gold in the fall. Neither the flowers nor the fruit are ornamentally significant. The peeling white bark is extremely showy and adds significant winter interest. This is a relatively low maintenance tree, and should only be pruned in summer after the leaves have fully developed, as it may 'bleed' sap if pruned in late winter or early.

4. Abies nebrodensis. The Sicilian fir, is a fir native to the Madonie mountains in northern Sicily (the largest island in the Mediterranean). It is closely related to silver fir, Abies alba, which replaces it in the Apennine Mountains of Italy and elsewhere further north in Europe; some botanists treat the Sicilian fir as a variety of silver fir, as Abies alba var. nebrodensis. It is a medium-size evergreen coniferous tree growing to 15–25 m tall and with a trunk diameter of up to 1 m. As a result of deforestation for farming, it is now extremely rare, with only 25 mature trees surviving; replanting programmes are meeting with limited success due to heavy grazing pressure by livestock belonging to local farmers. It was classified as 'critically endangered'. Since 1908 collections have been providing a lifeline for this tree.

5. Chamaecyparis lawsoniana 'Versicolor' or Versicolor False Cypress. This large cultivar ‘ Versicolor’ has green leaves with pale green to yellow flecked undersides, and is conical in shape. It has very open, spreading branches leading to sprayed foliage that is somewhat scaly. Can grow to a height of 40 m. Native of the mountains of NW California and SW Oregon between 4000 and 6000ft. It was introduced to Britain in 1854 and seeds were grown by Lawson seed merchants of Edinburgh.

6. Acer capillipes. Kyushu maple or red snakebark maple. It is a small deciduous tree growing to 10–15 m (rarely to 20 m) tall with a trunk up to 70 cm diameter, though usually smaller and often with multiple trunks, and a spreading crown of long, slender branches. It is grown as an ornamental tree for its striped bark and good autumn foliage. When grown together with its close relatives, it may be distinguished from them by the additional presence of small, rust-orange spots on the bark. The tree originates from Japan and was introduced to the United Kingdom in 1894.

7. Picea orientalis 'Skylands' or Oriental Spruce. 'Skylands' forms a graceful, narrow conical shape with beautiful bright golden yellow foliage on all outer shoots year-round and an eye-catching annual display of red male flowers. Native to the mountains around the eastern end of the Black Sea. The leading shoot should be trained up a cane. Makes a superb specimen tree and sometimes used as a Christmas tree. Grows to about 2.3 m in 10 years. Introduced into the UK in the 19 century around 1837. There are over 50 cultivars of Picea orientalis around the world.

8. Picea pungens 'Silver Tip' or Colorado or Blue Spruce. Pungens meaning sharp tip or pint (refers to the needle). Its natural range extends from northern New Mexico through Colorado and Utah to Wyoming and into Alberta and British Columbia, but it has been widely introduced elsewhere and is used as an ornamental tree. In the wild, Picea pungens grows to about 30 m. Often used as a Christmas tree in favour of the more traditional Norway Spruce because of the colour. UK records for introduction are limited, however, it is thought the Norway spruce was native to the UK in the last glacial period, and records show it was re-introduced as early as 1548. The Koster, best known for gardens, was produced in Holland in 1901.

9. Acer campestre 'Schwerinii' or Field Maple is a slow-growing deciduous tree with dark, oval leaves that turn yellow in the autumn. The 5 lobed leaves are composed of 3 to 5 entire lobes. The cultivar, 'Schwerinii' is a small tree with a narrow crown to 15 feet with purple to dark purple young leaves, becoming greener in the summer. The field maple is widely grown as an ornamental tree in parks and large gardens. The wood is white, hard and strong, and used for furniture, flooring, wood turning and musical instruments, though the small size of the tree and its relatively slow growth make it an unimportant commercial wood. The native range of field maple includes much of Europe, including Denmark, Poland and Belarus, England north to southern Scotland (where it is the only native maple), southwest Asia from Turkey to the Caucasus, and north Africa in the Atlas Mountains. Native to UK.

10. Ulmus davidiana var. japonica or Japanese Elm. The Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental northeast Asia and Japan. First discovered in 1873 in the hills of Beijing. The tree grows to a maximum height of between 15 and 20 m. Its bark remains smooth for a comparatively long time, before becoming longitudinally fissured. The leaves, often dark red on emergence.

11. Quercus cerris 'Argenteovariegata' or Variegated Turkey Oak. This varierty is an uncommon and very rare deciduous tree, which is distinguishable by this magnificent foliage; variegated green and white or cream edges. Despite its wide and spreading habit it does not exceed 8 to 12 m in height and is ideal to brightening up small and large spaces. The trunk has dark, blackish, deeply cracked bark. In spring and summer, the strongly cut leaves are dark green with a creamy white margin, they take on beautiful brown-yellow autumnal hues and persist for a long time on the tree. The acorns mature in September. Turkey Oak was introduced to Britain by J. Lucombe of Exeter in 1735. It is native to S Central and SE Europe, extending into SW Asia.

12. Quercus alba 'Elongata' or White Oak. The trees reach heights of 8 to 25 metres and are comparatively slow-growing and long-lived. Quercus alba produces spikes of brilliant greenish yellow flowers in April and May. Quercus alba is native to East Canada, the central Northeast of the US, the Northeast of the US, the southern Prairie States of the US, the Southeast of the US and Florida. Introduced into Europe in 1724.

13. Acer rubrum 'Wageri' or Red Maple. It is a tall, German cultivar with weeping, pendulous branches. With 10 m to 15 m height and conical growth, the red maple 'Wageri' is classified as a tree that forms a closed crown. The natural range of the species Acer rubrum is to be found in North America. The tree was introduced into the United Kingdom in 1656.

14. Quercus laurifolia or Laurel Oak. Quercus laurifolia is a medium to large-sized semi-evergreen species of red oak growing to 20 m tall. It is relatively short lived compared to other Oak tree species - 75 to 100 years. The oval acorns will only be produced on a tree that is between 15 and 20 years old and take 2 years to mature. It is native to the south-eastern and south-central United States, from coastal Virginia to central Florida and west to southeast Texas. Introduced into Europe in 1756.

15. Betula utilis var. jacquemontii 'Jermyns' Himalayan birch. It is a popular and extremely ornamental silver birch. It's medium-sized with an open habit and pyramidal shape. It bears almost shimmering white bark, which peels each year to reveal a fresh layer beneath. Himalayan birch's native range is centred on Nepal and the first trees were introduced to Britain in the 1880's. The Jermyns is the best of the jacquemontii cultivars and this tree was selected from a batch of seedlings received from Belgium.

16. Carpinus betulus 'Pendula Dervaesii' or Weeping Hornbeam. A slow growing and exceptionally beautiful weeping type of hornbeam that is unjustifiably little used. 'Pendula' is grafted onto a lower trunk of common Hornbeam. The height of the graft determines the eventual height of this solitary tree. The tree will easily reach a breadth of 4 - 5 m. The whole tree turns colour to golden yellow in the autumn. There are no flowers and therefore no fruit. Root growth is relatively close to the surface. The rotted leaves are good soil improvers. Hornbeam is native to UK.

17. Populus glauca or Big Leaf Poplar. The bluish-hued foliage of Populus glauca stands out among other trees, but does not emerge until June. This little-known poplar was described in 1906 from specimens collected in Sikkim, India. It also occurs in east Nepal. Introduced into the UK by a gentleman call Schilling in 1983 (he brought only 5 seedlings) this being the champion with 3 others at Wakehurst Place.

18. Photinia x fraseri 'Red Robin' or red tip photinia and Christmas berry. Red Robin grows at a rate of about 30 cm per year when established. It responds very well to pruning and can easily be kept to a suitable height. Common hedgerow plant and rarely used as a tree. It is native to North America and Asia. Photinia x fraseri, raised at Fraser nurseries in Birmingham, Alabama, in the 1940s, has a complex history, being a cross between Photinia glabra and Photinia serrulata. The cultivar 'Red Robin' is the most popular of commercial introductions. Raised in New Zealand and perfected in the Mediterranean country of Italy, it is both vigorous and hardy. Oddly, this species neither appears in my tree or shrub books and is clearly somewhere in between!