Peonies of the World - Look inside - Royal Botanic Gardens, Kew

62 PEONIES OF THE WORLD
1. PAEONIA LUDLOWII
Map 5.1. Distribution of Paeonia ludlowii (Stern & G. Taylor) D. Y. Hong.
unbranched stems to 8 feet (2.4 m) vs. 5 feet (1.5 m) in var. lutea, its larger and more open flowers,
with up to 2 carpels that are twice as large as those of var. lutea. These differences have been
confirmed upon examination of plants in five populations in Mailing and Nyingchi counties and
five populations of var. lutea (= P. delavayi). As shown in Hong (1997a: figs 1 and 2), plants of P.
ludlowii are tall from a caespitose base, and have relatively large, pure yellow flowers, yellow
filaments, acuminate leaf segments and lobes, and typically one carpel per flower (more than 97%
of the flowers examined had a single carpel and fewer than 3% had two). Furthermore, P. ludlowii
produces very large follicles that contain the largest seeds in the genus. By contrast, plants of P.
delavayi are not caespitose and have much shorter stems, acute leaf lobes and segments, smaller
flowers, yellow petals that are nearly always red-blotched at the base, purple-red filaments, and
three or four, rarely two, much smaller carpels. These differences clearly support the recognition of
the variety ludlowii as a distinct taxon and species.
Paeonia ludlowii is a tall shrub that often forms large and dense clumps with dozens of stems. A
single individual can have up to 105 flowers (Hong, 1997a: fig. 2). All of the five populations studied
were small in area, and the largest population was about 200 m in diameter. Except for the Quenima
Village population (D. Y. Hong et al. H96020), which had only four individuals, all the populations
observed consisted of many rather densely packed individuals, and the species was a dominant element
in the community. Two factors may explain the small population areas that contain a large number of
individuals. First, this species has a high seed-set, and its seeds appear to have a high germination rate.
Nearly 100 seedlings were found in an area of a square meter under a large individual in the Nanyigou
population (D. Y. Hong et al. H96030). Second, the seeds of P. ludlowii are large (ca. 1.2 cm diameter)
and are not adapted to long-distance dispersal; perhaps they are mostly moved by rats. The species is
Fig. 5.1A (opposite). Paeonia ludlowii (Stern & G. Taylor) D. Y. Hong: a, a shoot with a cyme and single carpels; b, a
seedling, showing hypogeal seed germination. Drawn by Miss LI Ai-Li.