Table 1 Characteristic morphologies of seven rhubarb species

R. tanguticum Maxim.

1.5–2 m

Small, purple or light red

Subcircular or broadly ovate, 30–60 cm long, narrow and pointed apex

About 5 splits, needle-shaped, closely to the base of the leaf

R. officinale Baill.

1.5–2 m

Large, yellowish-white

Subcircular, 30-50 cm in diameter, pointed apex

Shallow, only 1/5 to 1/4,

triangular shape

R. palmatum L.

1.5–2 m

Small, purple-red or yellow-white

Subcircular, 40–60 cm in diameter, pointed apex

About 1/3 to 1/4, triangular shape

R. franzenbachii Münter.

0.5–0.9 m

Yellow-white, 3-6 clusters

Cardiac ovate, 12–22 cm long, 10–18 cm wide, corrugated margin

Few or no

R. australe D. Don.

0.7–2 m

Purple-red

Oval-elliptic, 20–50 cm long, 18–40 cm wide, margin with weak wrinkles

Few or no

R. nobile Hook.f. & Thomson.

1–2 m

Yellow-green, 5–9 clusters

Lotus-shaped, 20–30 cm in diameter, round apex

Few or no

R. wittrockii C.E. Lundstr.

0.5–1 m

White-green, small, 2 mm in diameter

Ovate, 15–26 cm long, 10–20 cm wide, obtuse and acute apex, margin with weak wrinkles

Few or no