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Nystroemiaceae †

The Nystroemiaceae are Permian gymnosperms with ovulate structures showing some apparently ancestral features more typical of early seed plants, whereas the leaves and branches show derived character states of broad-leaved gymnosperms

Ecology & Form

Stems

Branches were probably woody with variability in its branching pattern
Long and short shoots were differentiated

Leaves

Vegetative leaf with a long petiole and a broad lamina with radiate reticulate venation
Lamina with entire or undulate margin and cordate or tapering base

Reproductive Structures

Frond-like ovuliferous organ
The main axis forking with pinnate lateral branches bearing numerous small bicornute ovules at their tips.
Leafy/ovuliferous complex arising from leaf axil
Ovuliferous organs attached in the axil of the petiole of leafy organ, or both organs crowded on a node

Classification

└Lignophytes

└Nystroemiaceae †

Geologic Age

Middle - Late Permian

Nystroemia †

Halle 1929; Wang & Pfefferkorn 2010
Early - Late Permian of North China
Seed plant with multi-order branching system
Ovuliferous organ frond-like, with the main axis forking into two or more pinnate branches adaxially bearing numerous small bicornute ovules with zygomorphic symmetry
Vegetative leaf with a long petiole; lamina reniform, basally cordate or tapering, entire or slightly undulate at the margin; veins numerous, finely diverging and reticulate.
Leafy/ovuliferous complex arising from the leaf axil, forming the last-order branches, which are alternative or opposite on the second-last-order axis
Ovuliferous organs are attached in the axil of the petiole of the leafy organ, or both organs are crowded on a node.

N. reniformis †

Wang et al. 2003

N. shouyangensis †

Wang & Pfefferkorn 2010
Middle - Late Permian (Capitanian–Wuchiapingian) of Shouyang, Shanxi, China
Ovuliferous organ with the main axis forking into two or more pinnate-like branches adaxially bearing numerous small bicornute ovules with zygomorphic symmetry
Vegetative leaf with a long petiole; lamina reniform, basally cordate, entire or slightly undulate at the margin; veins numerous, finely diverging and reticulate
Leaves and ovuliferous organs attached to short shoots, forming the last-order branches

The most critical difference is that N. shouyangensis has leaves and ovuliferous organs arranged on a short shoot, whereas N. reniformis are arranged on a long shoot
The leaf laminae of N. shouyangensis have a very distinctly cordate base, whereas N. reniformis mostly have a wedge-shaped lamina base, although the lamina base of certain small leaves is cordate to a degree
The ovuliferous organs of N. shouyangensis as a rule appear as a main axis that distally bifurcates once, producing two subordinate pinnate branches bearing numerous small bicornute ovules, whereas N. reniformis are more irregular

Above: Nystroemia reniformis † (From Fig. 4, Wang & Pfefferkorn, 2010)

Above: Nystroemia shouyangensis † (From Fig. 6, Wang & Pfefferkorn, 2010)

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