Monthly Masterclass: November

Identify it: Autumn Leaves

Liquidambar styraciflua (1), Acer palmatum ‘Osakazuki’ (2), and Acer saccharinum (3), photograph by Leighanne Gee

Acer palmatum, the Japanese maple, is indispensable. Its reliable display of fiery colour is surpassed perhaps only by one other garden tree; Liquidambar styraciflua (1), the sweet gum, which turns crimson first at its tip preceded beneath by seamless gradations of green and yellow. The two share many superficial similarities leading to frequent confusion. Both have palmate leaves meaning that each is lobed in the shape of an outstretched hand. Acer palmatum ‘Osakazuki’ (2) has 5-7 lobes in common with the Liquidambar. However, they are much more shallowly divided reaching only half way to the leaf base. The arrangement of the leaves themselves leaves no doubt as to which is which. Liquidambar leaves appear alternately along the stem whilst those of the maples appear opposite each other in pairs. For those that wish for subtler autumn tones, there is Acer saccharinum (3), the silver maple, which is distinguished from other maples by deeply divided 5 lobed leaves with jagged saw-toothed edges that turn a soft-yellow before they fall. Most distinct are the petioles which join the leaf to the stem. These are extremely long in relation to the size of the leaf and result in a shimmering effect as the delicately poised leaves quiver constantly even in the gentlest breeze.

Taxodium distichum (1), Taxodium distichum var. imbricatum ‘Nutans’ (2), and Metasequoia glyptostroboides (3), photograph by Leighanne Gee

Coniferous trees are most highly prized for their evergreen presence meaning that deciduous species are often forgotten. Those that can accommodate Taxodium distichum (1), the swamp cypress, or Metasequoia glyptostroboides (3), the dawn redwood, will be rewarded in autumn with reds and browns found in few other broad-leafed species. These trees are also easily separated by the arrangement of their leaves. Both have linear, flattened leaves which appear on pinnate branchlets, meaning that each individual leaf appears either side of a central axis. On Taxodium, both these individual leaves, and the branchlets they comprise, appear alternately to one another, whilst on Metasequoia, they appear opposite in pairs. Taxodium distichum var. imbricatum ‘Nutans’ (2) produces the same brick-red autumn colour as its near relative but its needles are easily identified as distinct. Imbricatum means ‘overlapping’ and nutans means ‘nodding’. Both refer to the adpressed leaves, pressed against the stem along crowded, drooping branches.

Fagus sylvatica (1), Carpinus betulus (2), and Ostrya carpinifolia (3), photograph by Leighanne Gee

Of all the deciduous trees Fagus sylvatica (1), the beech tree, hangs onto its leaves the longest. Like deciduous conifers, its coppery-brown tones give warmth to the landscape as either tree or hedge. Carpinus betulus (3), the hornbeam, proves an equally popular hedging plant providing much the same effect, although its autumn leaves contain hints of yellow and orange, and fail to hold long into the winter. Members of separate families, Fagaceae and Betulaceae respectively, both are best discerned from one another when still in full leaf. Both have leaves arranged alternately along the stem but those of Fagus sylvatica are a deeper, glossier green, with only shallow undulations interrupting the leaf’s edge. The leaves of Carpinus betulus are a lighter, less glossier green, with a sharply serrated edge. The presence of Ostrya carpinifolia (2), the hop hornbeam, could lead to further confusion. Carpinifolius means ‘leaves like a Carpinus‘ indicating the similarities between the two. However, the distinctive fruits it produces, papery scales which overlap like those of Humulus, the hop plant, reveal it as a member of a genus all of its own.

Grow it: Dwarf Conifers

What: Dwarf conifers are those which usually grow less than 1 metre tall in 10 years. They come in a variety of shapes and colours forming low mounds or narrow upright trees in an equal array of colours from green, blue, yellow or variegated.

Juniperus communis ‘Compressa’ gives structure to alpine troughs

Where: Smaller gardens which require a clearly defined focal point but lack the room to accommodate an ordinary sized tree. Rock and scree gardens will be equally enhanced by their presence, as will the winter garden, where evergreen structure is essential.

How: Grow dwarf conifers in a free draining soil in sun or part-shade. Keep newly planted specimens well watered initially. Once established apply an annual application of slow release fertiliser followed by mulch.

When: Plant from October to April whilst plants remain dormant. Semi-ripe cuttings can be taken in late-summer and hardwood cuttings in winter. Keep checking variegated plants for non-variegated reversion which can be removed from spring to late summer.

The Gardener’s Verdict:

“I love dwarf conifers, but it has to be accepted that some ‘dwarf’ conifers are just slow-growing whereas others are genuinely small. When you buy a dwarf conifer, on the label it normally gives you the ‘height in 10 years’. This does not mean it stops growing after 10 years. This is not the final height!

Some conifers have an incredibly slow growth rate and do remain compact. My favourites are the gorgeously proportioned Pinus mugo cultivars; ‘Gnom’, ‘Humpy’, ‘Mops’, and ‘Mops Midget’. I also love Abies but these tend to be slow-growing rather than genuinely compact. Abies koreana ‘Oberon’ starts off with a rounded shape, becoming an elegant conical form.

Dwarf conifers work well with low carpeting plants such as Phloxdouglasii ‘Crackerjack’ or Dianthus ‘Bath’s Pink’. The most important thing is to think about scale; if you want bulbs under them choose dwarf cultivars like Narcissus ‘Tete-a-Tete’, with herbaceous perennials choose smaller cultivars such as Persicaria affinis ‘Superba’. The combination of dwarf conifers and heathers may be considered by some a bit 1970s, but it does work!

Evergreen interest can be created in a similar way using small-leaved shrubs such as Buxus sempervirens, Ilex crenata or Lonicera nitida. Clipping these shrubs can also provide a variety of forms, and has the advantage of keeping them small.”

Abby Gulliver, Glasshouse Area Supervisor, Winterbourne House and Garden

Read it: Powered by Plants

Winterbourne’s annual ‘Steam Day’ is one of the most popular events in our calendar as hundreds of toy steam enthusiasts descend upon the gardens. In October, the nearby Lapworth Museum of Geology helped us to explain why the steam engines on show, are ultimately ‘Powered by Plants’.

Leaves of an ancient horsetail, photograph by the Lapworth Museum of Geology, University of Birmingham