A shrub 1–2 m tall, with narrow ascending stems from wide-ranging rhizomes, with glabrous stems and twigs; the plant is often glaucous with whitish wax on the stems and leaves, diminishing as they age. Leaves deciduous or sub-evergreen, spirally arranged; petiole 3–6 mm, lamina coriaceous, dull green but often glaucous, 2–8(–10) × (0.5–)1.2–4.5 cm, elliptic to elliptic-ovate or ovate, base cuneate, apex acute to rounded, margins irregularly and shallowly serrulate-crenulate or entire, surfaces finely hairy when young, becoming glabrescent. Inflorescences borne as axillary racemes of (2–)5–12-flowered corymbs, or solitary flowers, at the tips of the previous year’s shoots. Flowers white (occasionally pink-flushed), bell-shaped, scented of aniseed; sepals 5, separate, triangular; corolla 6.5–12 mm long, 5-lobed, with the lobes free for about 1/4 of the length of the corolla; stamens 10, with straight, flattened, glabrous filaments; anthers with 4 awns; style truncate on a 5-partite style; ovary 5-locular, becoming an erect, dry, rounded 5-valved capsule containing 40–200 unwinged seeds. Flowering in spring (USA), early summer in UK. (Bean 1981, Tucker 2009)
Distribution United States Georgia, South Carolina, North Carolina, Virginia
Habitat Coastal plains, usually in damp places in pine savannas and shrub bogs, 0–100 m asl.
USDA Hardiness Zone 5-9
RHS Hardiness Rating H6
Conservation status Not evaluated (NE)
‘With fragrant flowers like large lilies-of-the-valley and glaucous young stems and leaves this is one of the loveliest of ericaceous shrubs’ – Bean’s summary (1981) can hardly be bettered. Despite its origins in the low-lying, very hot and humid coastal plain of the southeastern United States, it is remarkably tolerant of much cooler conditions elsewhere, thriving throughout even the cool summer areas of Britain, though always preferring ample moisture in acidic soil. Full sun will encourage the best autumn colours to develop, although they often do not turn (to yellow through to good bronze-reds) until very late in the year. Bean notes, however, that it is prone to late frost damage (hardly unique to Zenobia!), and Dirr (2009) records that it can suffer severe winter damage in Maine. It was introduced to cultivation in Britain around 1800, with a glaucous plant figured for Curtis’s Botanical Magazine in 1802 (t. 667, as Andromeda pulverulenta) grown by ‘Mr Fraser in Sloane Square’; and the same gentleman provided a green-leaved plant a few years later (t. 970, as Andromeda cassinefolia) (see Biodiversity Heritage Library). This was John Fraser (1750–1811) who founded the American Nursery in Sloane Square in the 1780s, and himself collected American plants (Desmond 1994) – it is probable that the introduction of Zenobia can be attributed to him. Despite this history it is curiously unfamiliar. Successive editions of the Hillier Manual (Hillier & Coombes 2002, Edwards & Marshall 2019) have suggested that this is because it flowers during the London ‘Season’ and thus must have been overlooked…
Lovely though the flowers are, the chief merit of Zenobia lies in its new foliage, though the leaves can also turn to good colours in autumn. Most cultivated stocks have been selected for their glaucescence, the white wax giving a lovely bluish effect to the young leaves that is conspicuous in the garden, especially among other ericaceous plants. It loses some of its brightness as the season goes on. In the wild such glaucous forms are said to occur principally in the inner coastal plain areas of the Sandhills region of North Carolina and South Carolina, with green-leaved plants occurring to the eastward (Tucker 2009). These have been named f. nitida (Michx.) Fernald, or var. nuda (Vent.) Rehder, but there seems to be some uncertainty as to the separation of green from glaucous plants in the wild, and Bean (1981) says that seedlings vary in their glaucescence. For this reason he recommends propagation of selected clones by semi-ripe cuttings rooted in moderate heat in July. A number of clones have been selected for their foliage quality; several are described below, but others such as ‘Billowy Blue’, ‘Christoff’ and ‘Oree’ are apparently no longer commercially available (Hatch 2018–2020).
Zenobia pulverulenta 'Blue Skies'
‘Blue Sky’ is widely available on both sides of the Atlantic, it seems, but its origins are mysterious. The earliest known citation found by Hatch (2018–2020) is an entry in the 2001 Fa. C. Esveld catalogue. As its name suggests, it is a particularly good glaucous clone. ‘Blue Skies’ appears to be a variant spelling of the name; ‘Misty Blue’ may be the same thing (K. Cox, pers. comm. 2021).
Andromeda speciosa var. nitida Michx.
A. cassinefolia Vent.
A. cassinefolia var. nuda Vent.
Zenobia speciosa (Michx.) D. Don
Z. pulverulenta var. nuda (Vent.) Rehd.
Z. cassinefolia (Vent.) Pollard
Text unchanged (2021) from Bean 1981: In all essential characters this is identical with typical Z. pulverulenta, but the leaves are green on both sides and the stems are scarcely glaucous. Bot. Mag., t. 970. This green-leaved form is less striking than the typical glaucous form, but still charming. It received an Award of Merit in 1934 as Z. speciosa and in 1965 as Z. pulverulenta var. nuda. It is still usually known in gardens as Z. speciosa, but is certainly not specifically distinct from Z. pulverulenta and, if it were, it would take the name Z. cassinefolia.
A good glaucous-leaved clone, of unknown origin. Ken Cox of Glendoick Gardens and Nursery, informs us (pers. comm. 2021) that their stock plants came from RareFind Nursery, New Jersey: Glendoick has sold this clone for some years and was the source of the plant at the Yorkshire Arboretum illustrated here. However, Ken says that he has been told that it is the same as ‘Blue Sky’.
(Bean 1981) This has the leaf-margins set with shallow wavy lobes. A curiosity.
Bean’s text, though cited as 1981, was retained unchanged from the first edition (1914) and this cultivar or form seems to have vanished long ago.
According to Dirr (2009) this was first listed by Heronswood Nursery, Washington, in 1998, apparently their own selection. It appeared fitfully in Heronswood catalogues over the following few years, but is now quite widely available from British nurseries, at least. Its main point of distinction is the pink flush evident in the buds, and persisting as a stripe on the corolla lobes as the flower matures. It is a green-leaved plant, and capable of excellent late bronze-red colour (Dirr 2009).
A selection with good glaucous foliage made by Bob McCartney of Woodlanders Nursery, Aiken, South Carolina, prior to 1985 (Dirr 2009, Hatch 2018–2020). Michael Dirr regards it as ‘a knockout plant for foliage effect’, including its late red-purple autumn colouring. He also notes that (at least in the southeastern United States) it needs a particularly reliable moisture supply.