The defining plants of my pre-teen years were those that grew in the garden of my parents’ 1930’s semi-detached house in Plymouth. Climbing the walls were Rosa ‘Masquerade’ and R. ‘Albertine’, a delicious loganberry and a variegated honeysuckle which resolutely failed to flower. In the borders there were African marigolds in summer and crocuses in spring, planted in small round beds beneath standard roses: ‘Peace’, ‘Iceberg’ and ‘Fragrant Cloud’. Hedges were fashioned from golden privet and red escallonia, and the walls along the drive were thronged with red valerian (Centranthus ruber) and an ineradicable weed we called bread and cheese. That plant had soft, ferny, light green foliage and clear yellow flowers sprouting from pinkish, succulent stems. It was the favourite gathering place for local snails, providing cool, lush cover, out of harm’s way. Its persistence made it part of the garden’s fabric. Although I can find no reference to it ever being referred to as bread and cheese by anyone else, I know the weed’s name: Corydalis lutea.
Corydalis lutea (known to most as yellow fumitory), is one of those plants, like Erigeron karvinskianus or Meconopsis cambrica, that once you have it established in a wall or terrace you will never be rid of. That’s not all bad as it’s a pretty filler, but one can definitely have too much of a good thing. Yellow fumitory loves the West Country climate, which is generally damp and cool. Like so many plants, Corydalis lutea appreciates good drainage, hence a penchant for walls and rockeries. Having come up short on finding any of my own photographs of the subject in hand, I stumbled upon this one on Pinterest, demonstrating both its rapacity and its ability to act as an effortless groundcover in semi-shaded situations. Although a great visual companion for hostas, I cannot recommend it if you are susceptible to snails.
Corydalis is a genus of about 470 species of annual and perennial herbaceous plants in the Papaveraceae family, native to the temperate Northern Hemisphere and high mountains of tropical East Africa. They are most diverse in Asia and the Himalayas, with at least 357 species originating in China. The name Corydalis comes from the Greek korydalís, which means ‘crested lark’. This refers to the delicately balanced, bird-like poise of each individual flower on the stem. Others compare them to shoals of colourful tadpoles navigating a sea of fine foliage. Corydalis flowers cover a wide colour spectrum, including red, pink, coral, orange, yellow, purple and, famously, blue.
Corydalis solida has been planted in gardens since at least the sixteenth century. It has mauvish-pink flowers and naturalises well in grass or amongst spring-flowering bulbs. Imagine it with bluebells, primroses or late flowering narcissi and then go and plant some! Two weekends ago I admired Corydalis solida subsp. solida ‘Beth Evans’ in the Lower Courtyard at Sissinghurst. This cheerful variety produces delicate, pink-spurred flowers and rarely tops six inches in height, making it ideal as an edging plant. Later in the year the foliage dies back quickly, allowing other plants to occupy the same space. Anyone craving redder flowers might try Corydalis solida subsp. solida ‘George Baker’, which has brick-red flowers that vary in colour depending on the quality of the plant and the coldness of the preceding winter. The clone was originally discovered in Romania, from whence most of the pink and red forms hail. Corydalis solida ‘Zwanenburg’ is considered the finest red form, and has been known to change hands for three figure sums.
Personally I like the quieter colours in Corydalis, especially the hybrids between Corydalis solida and sulphur-flowered Siberian native Corydalis bracteata, known horticulturally as Corydalis × allenii. These produce pale, creamy-yellow, mauve-suffused blooms above luxuriant, silver-grey leaves. Quite the most elegant fumitories you’ll ever see.
Now, to the attention-grabbing blues from Eastern Asia. The most common is Corydalis flexuosa, which has an Award of Garden Merit from the RHS. Plants have finely divided, glaucous foliage, sometimes tinged with purple. Flowers are electric blue, often tinged with purple, and are utterly irresistible. The form ‘China Blue’ has heavenly, glacier-blue flowers that carry on from spring until July. ‘Purple Leaf’ produces mounds of smoky-blue foliage and azure flowers flushed with red. If you can track them down, Corydalis ornata and Corydalis turtschaninovii are other interesting blues.
Thirty years on I find myself without any corydalis in my gardens at all, a position I am eager to remedy. Flowering in spring and early summer, Corydalis tend to have disappeared underground by midsummer, making them an ideal partner for hostas, deciduous ferns, grasses and other perennial plants which come into leaf later in the year. Corydalis will grow nicely in pots of gritty, humus-rich soil, but must be kept cool and moist in summer, otherwise they will succumb to mildew faster than you can say ‘Jack Robinson’. The one I covet most is Corydalis cheilanthifolia, pictured below in the Cottage Garden at Sissinghurst, a plant one might easily mistake for a flowering fern, if such a thing existed. The leaves are finely dissected and flushed with red in spring, whilst the flowers are produced in thick, upright plumes of canary yellow. Quite a sight, even in the most exotic of gardens.
There are two National Collections of Corydalis; one in Durham, and one in Clacton-on-Sea. A comprehensive selection of seldom-found and unusual Corydalis is offered by Rare Plants in Wrexham, North Wales. Do let me know if you grow Corydalis and I have left any of your favourites out. TFG.