Rhododendron stenopetalum 'Linearifolium'

A 300-year-old Japanese garden cultivar that doesn't look quite like a rhododendron, doesn't look quite like an azalea, and doesn't really look like anything else. The leaves are narrow ribbons — three to five millimeters wide and a couple inches long, more like willow or fine grass than the broad rounded foliage of a typical tsutsuji. The flowers, when they open in late April or May, are constructed in the same vocabulary: deeply divided into long strap-like petals in lilac-pink to lavender-rose, often appearing tangled or knotted at first and unfurling slowly into something that resembles, depending on your eye, a crane fly, a spider, or a piece of decorative sushi garnish. Wabi-sabi made evergreen.

This is one of the great oddities of Japanese horticulture. Azaleas have been bred and refined in Japan since at least the Kamakura period (1185–1333), and seriously selected through the Edo era — Japan's first dedicated book on azaleas, Kinshu Makura (A Brocade Pillow), was published in 1692 and codified hundreds of named cultivars. 'Linearifolium' is a survivor of this old tradition: a sport selected and propagated entirely by gardeners, never found in the wild, only existing because someone, centuries ago, decided this version was worth saving. The Japanese name 'Seigai Tsutsuji' (青海躑躅, "blue-sea azalea") gestures at the rippling effect the narrow foliage makes en masse.

It's been shuffled through three Latin names over the years — first Rhododendron linearifolium, then R. macrosepalum 'Linearifolium', and now correctly R. stenopetalum 'Linearifolium', though it still circulates in the trade under all three. Slow-growing, eventually reaching 3–4 feet, with a soft and slightly tousled shape that takes well to pruning into more architectural forms or left loose for a quieter, more relaxed effect. Holds its leaves through mild winters, often picking up wine-red tones in cold months before reverting to mid-green in spring.

Not a plant for filling space. A plant for the spot where you want someone to slow down and look — the corner of a courtyard, a Japanese garden bed, beside a teahouse or a stone lantern, anywhere proximity rewards close attention. Good rootstock for the gardener who already has a couple of the wide-leaved azaleas and is ready to move beyond them.

Photos courtesy of Joanna Kossak