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

PEONIES OF THE WORLD
CHARACTERS AND THEIR VARIATIONS
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at the apex. For all other species, i.e. most species in sect. Paeonia, the gradation is more or less
interrupted. The sepals are mostly non-caudate and thus more or less distinct from bracts, though
inconsistent in shape and size (Fig. 3.12e,f ).
The bracts-sepals series is of certain taxonomic value. Because of their similar leaflets (or leaf
segments), Paeonia intermedia and P. anomala had long been confused before Hong and Pan (2004)
found that P. intermedia has most of its sepals rounded at the apex (Fig. 5.26B), whereas P. anomala
has all or most of its sepals caudate at the apex (Fig. 5.14B). This character is closely correlated with
root shape (Figs 5.14A, 5.26A). Using these two characters, the two species are readily
distinguished.
The bracts-sepals series also reflects the systematic position of a taxon within Paeonia; in
general, a gradual gradation of the bracts-sepals series with most or all of the sepals caudate at the
apex is correlated with primitive characters, such as woody habit, multi-flowered stems (shoots)
and diploidy.
3.9 NUMBER OF FLOWERS PER SHOOT
This character is described relatively easily. In sect. Moutan, the shoots of Paeonia ludlowii and P.
delavayi are constantly multi-flowered, whereas flowers in the other six species are solitary and
terminal. In section Onaepia, the two species, P. brownii and P. californica, are both multi-flowered,
though the flowers often look solitary and terminal. One or two undeveloped (sterile) flower buds
can often be found in the axils of the upper leaves. For these two sections, there is no taxonomic
problem caused by misunderstanding of this character.
In sect. Paeonia, however, all the species except those mentioned below consistently have
solitary flowers. Paeonia lactiflora and P. emodi are both described as multi-flowered and cause no
taxonomic problems. Problems occur only in the P. anomala–P. veitchii group. Paeonia anomala was
described as single-flowered (Schipczinsky, 1937; Pan, 1979), whereas P. veitchii was described as
multi-flowered (Lynch, 1909; Pan, 1979). The demarcation between these two species was made
on the basis of this single character. It is true that P. veitchii (= P. anomala subsp. veitchii) often has
multi-flowered stems, but single-flowered stems with one or two undeveloped flower buds in axils
of the upper leaves are also often found, and single-flowered stems occur very rarely without any
additional undeveloped flower buds. Such individuals have been described as a variety, P. veitchii
var. uniflora K. Y. Pan (1979). In P. anomala (= P. anomala subsp. anomala), flowers are nearly always
solitary, but, besides the terminal flower, one or two undeveloped flower buds can sometimes be
found in axils of the upper leaves, and very occasionally there are two flowers on a stem. Paeonia
altaica K. M. Dai & T. H. Ying (1990) was based on such an individual. In our observation of
specimens from the site in the Altai (Wuzkiliti, Habahe County) where the type was collected,
three kinds of individuals coexisted: single-flowered without any additional undeveloped flower
bud, single-flowered with one or two undeveloped flower buds, and two-flowered. Plainly, the
character of flower number varies in the P. anomala–P. veitchii group. We therefore treated the
group as a single species with two subspecies isolated by the Gobi.
3.10 PETALS
3.10.1 PETAL COLOUR
This character has been frequently used in the taxonomy of Paeonia. Many taxa were described on
the basis of petal colour, e.g. P. lutea, P. delavayi var. atropurpurea, P. delavayi var. alba and P. japonica
(which is white whereas P. obovata is pink). An extreme case is Kemularia-Nathadze’s