Primula Harbinger Group
Listed in the 2017 Plant Finder by only two nurseries, this charming primrose was added to the Conservation scheme in 2002 by the Shropshire Group as it was an old selection and seldom grown. Primroses were popular in Victorian times and uncommon forms were eagerly sought along the lanes and hedgerows where they grew abundantly. Bearing pure white flowers with gold-centres, this sport of our native wild primrose, was found more than a hundred years ago in a Cornish wood, and awarded a First Class Certificate by the RHS in 1882.
Primroses are native to the British Isles and widespread throughout the west of Britain and Ireland, preferring a heavier soil and damp partly shaded areas, typically found in broadleaf woodland and along hedgerows. Being shallow-rooted they do not cope well with prolonged dry conditions on lighter soils. Flowering typically from late winter to mid spring, (although flowers can appear sporadically all year), primroses are the quintessential harbinger of spring as evidenced in the writings of Milton and Shakespeare among others and have a special association with Easter. Primroses were described in Gerard's Herbal, published in 1597, and have been used medicinally and for culinary use.
Primroses are rosette hemicryptophytes (perennial plants that bear overwintering buds at soil level where they are often covered by surface debris). This compact rosette (the older name, Primula acaulis, given originally by Carl Linnaeus in 1753 means stemless, but was changed to its currently accepted scientific name Primula vulgaris by English botanist William Hudson in a 1762 publication) produces short-stemmed green leaves up to 20cm long that have a wrinkled surface and slightly toothed margins. The flowers, typically 2-4cm diameter, each have 5 notched petals and are borne singly on a slender stem. Although predominantly pale yellow, some flowers may be white, whilst others have a pink or purplish tinge. Flowers exist in 2 genetically determined morphological forms, with either a prominent style and short anthers, 'pin', or with a shorter style and more prominent anthers, 'thrum'. Reproduction is mainly through seed with fertilisation occurring between a 'thrum' and a 'pin'-eyed flower. Pollination is mainly by bumble and other bees, but other long-tongued pollinators such as hover flies, bee flies and even butterflies may be important. Seeds are distributed by ants and rodents. Vegetative spread is restricted and only occurs within very short distances from the mother plant through the production of lateral rosettes.
Clearly this means that characteristics do not remain constant in seedlings. Barnhaven Primroses sell seed of P. Harbinger Group, but have been keeping this strain pure through hand pollination for over 60 years. This is important for the HPS Conservation Scheme and growers should look carefully at plants they have to see whether the flowers are as distinctive as described, particularly as there is no record of where the original plant or plants were obtained.
Plants for the Conservation Scheme should be vegetatively propagated and this is not difficult. When the main flush of flowers comes to an end in mid to late spring the plant should be dug up and the crown broken into separate pieces - each part growing into a new plant. These offsets can be potted up or planted out into good soil and kept moist until established. Plants seem to benefit from dividing fairly frequently, discarding the older, woodier prices at the centre of the crown. Mature plants benefit from tidying by removal of dead and damaged leaves. They are relatively trouble-free in the garden, but vine weevil grubs may kill plants in pots by feeding on the short rhizomatous part of the rosette.