Fern-leaf Peony

Paeonia tenuifolia is a hairless herbaceous perennial plant with a stem of 30–60 cm high, which is densely set with alternately arranged compound leaves. The lowest leaves are twice compounded or the leaflets are deeply divided into many fine linear segments, ½-6 mm wide, with a blunt to rounded tip, dark green above, and lighter glaucous green below. The usually single flower on each stem seems to be floating on the foliage. The flower is 6–8 cm across, cup-shaped, with deep crimson, long inverted egg-shaped petals, with a rounded or blunt top. The stamens are 1½—2 cm long, with yellow filaments, anthers and pollen. There are usually three, sometimes two, coarse felty haired carpels, that will eventually develop into 2 cm long, dry, dehiscent fruits called follicles. This species is diploid with ten chromosomes (2n=10).

P. tenuifolia flowers earlier than other peonies, and dies down early too. This is probably because it grows in steppes, with dry and hot summers. The seeds of this species germinate above the soil in full light, which is exceptional among peonies. The caterpillars of the moth Pelatea klugiana feed on the leaves of several Paeonia species, including Paeonia tenuifolia. Several larvae live together in a nest of silk that binds together several lobes of a leaf, and move only within the nest.

This hardy species is an attractive plant for the garden which is easy to grow and hardy in temperate zones. Still, as an inhabitant of the steppes of southern Russia and Kazakhstan, it is adapted to growing in the full sun and experiencing cold winters, and dry, hot summers, and it is susceptible to moult development on its leaves during prolonged wet spells. It has been in cultivation in Germany since 1594, and was introduced to England in 1765 and America in 1806. There are several cultivars and hybrids known to be in cultivation:

Paeonia tenuifolia 'Rosea' has pink flowers Paeonia tenuifolia Rosea Plena' with double pink flowers Paeonia ×smouthii, a presumed hybrid with P. lactiflora, which was commercially introduced in 1843, and sometimes listed as P. laciniata in nursery catalogues. It is taller than P. tenuifolia, and usually has more than one flower per stem with a sweet perfume, traits inherited from P. lactiflora. It is a diploid, and does not produce fertile seed. It was probably named in honor of M. Smout, a professional chemist at the Catholic University of Mechelen, who was an active breeder of plants. Paeonia ×majko, a presumed hybrid with P. daurica, found in Georgia, is not deemed particularly appealing. P. tenuifolia var. plena, a variety with double flowers, is said to have been introduced to English gardens in 1765. P. …