러들로모란-[정명] Paeonia ludlowii (Stern & G.Taylor) D.Y.Hong

Paeonia ludlowii is a deciduous shrub of medium height, belonging to the tree peony section Moutan of the genus Paeonia, and endemic to southeast Tibet. In Tibet it is known as ≠'lumaidao' meaning "God's flower". The vernacular name in Chinese is 大花黄牡丹 (da hua huang mu dan) meaning "big yellow-flowered peony". In English it is sometimes called Tibetan tree peony or Ludlow's tree peony. It has pure yellow, slightly nodding, bowl-shaped flowers, and large, twice compounded, light green leaves.

Description

P. ludlowii is a hairless, deciduous shrub of 2-3.5 m high. It has ten chromosomes (2n=10).

Stems and leaves

The roots become narrower further down and are not fused together. There are no creeping stems (or stolons). The grey to light brown stems grow in clumps from a gnarled root crown, seldom branch, remain approximately the same width during the growing season, and after some years may reach 4 cm in diameter. Young stems are light green, with at their base eight to twelve scales. Leaves are light green above and glaucous pale green below. In the lowest leaves, the leaf stalk is 9–15 cm long, while the leaf blade is twice compounded or deeply divided (or biternate), with the primary leaflets on a short stem of 2–3 cm, the leaflet blades 6-12 × 5–13 cm, those usually incised almost to the base, having three segments, at base extending along the stalk until disappearing (or decurrent). Each of the segments 4-9 × 1.5-4 cm, mostly incised to midlength into three lobes of 2-5 × .5-1.5 cm, with an entire margin or one or two teeth, pointy at their tips.

Inflorescence

Inflorescence viewed semi-laterally to show both interiors and exteriors of flowers

The slightly nodding bisexual flowers grow three or four to a shoot, the shoots springing from the leaf axils. The flowers are 10–12 cm wide, are borne on a pedicels 5–9 cm in length, and open in late May and early June. Each flower is subtended by four or five lance-shaped bracts. There are three to five green sepals with a rounded outline of 1.5-2.5 cm, which have a rounded tip narrowing abruptly to a point. The pure yellow, inverted egg-shaped petals are spreading but slightly curved inwards, 5-5.5 × 2.5-3.5 cm and have a rounded tip. The numerous filaments are yellow, 1-1.5 cm long, topped by yellow anthers about 4 mm in length . The yellow disk at the base of the carpels is ring-shaped, bears teeth, and stands about 1 mm in height. At the centre of each flower are one or two carpels that are topped by yellow stigmas.

Fruit and seed

The carpels develop into cylindrical fruits (or follicles) of 4.7-7 × 2-3.3 cm. These dehisce in August to reveal large, dark brown, globose seeds measuring 1.3 cm in diameter.

Differences from related species

Paeonia delavayi is closely related to P. ludlowii, but can easily be distinguished because it reproduces mainly by stolons, has fused roots, stems emerge from the ground individually, is only up to 1¾ m high, has segmented leaves with narrow and acute segments. Petals, stamens, disk, and stigmas may be yellow, maroon, orange or white. It has two to eight carpels, which develop in small follicles (2-3.5 × 1-1.5 cm) and rarely produce seeds. P. ludlowii on the other hand can only reproduce by seed and lacks creeping underground stems, has slender, regular roots, while the stems form a clump, grows to 2-3.5 m high, has leaves with short and abruptly pointed lobes, petals, stamens, disk and stigmas are always yellow, only one or very rarely two carpels develop but this grows into a much larger follicle (4.7-7 × 2-3.3 cm) which always develops seeds.

Other species of tree peony do not have yellow flowers, do not grow as large and generally have darker green foliage and darker brown bark. Some of the many cultivated cross-breeds of tree peonies may have yellow flowers, but these are not nodding, generally much larger, mostly double flowered, with darker green leaves and much lower.