Magnolia Family (Magnoliaceae)

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The Magnolia Family (Magnoliaceae)

A Primitive Family Of Flowering Plants

The earliest known flowering plants date back to about 130 million years ago. According to Cronquist (Evolution and Classification of Flowering Plants, 1988), the most primitive of all living angiosperms belong to the subclass Magnoliidae. This subclass contains several primitive plant families, including the water-lily family (Nymphaeaceae), buttercup family (Ranunculaceae) and magnolia family (Magnoliaceae). The magnolia family has the following primitive characteristics: (1) Large flowers with numerous petals and sepals (called tepals because they are similar in size and shape); (2) Numerous spirally arranged stamens at the base of a conelike receptacle bearing numerous spirally arranged carpels. At maturity the carpels develop into a woody, conelike aggregate of seed-bearing follicles. Each seed has a fleshy red outer layer (aril) and hangs from its follicle by a threadlike stalk. Other primitive floral characteristics are radial symmetry or actinomorphic (floral parts similar in size & shape), perfect (with functional androecium and gynoecium), complete (with all 4 floral parts: calyx, corolla, androecium & gynoecium), and floral axis (receptacle) elongated. The latter characteristic is clearly visible in the magnolia blossom. With all the woody, spirally arranged carpels (follicles), this axis truly resembles a conelike structure.

Large blossom of the southern magnolia (Magnolia grandiflora), a beautiful shade tree native to the southeastern United States. The numerous sepals and petals are called tepals because they are similar in size and shape. The conelike receptacle in the center is composed of numerous spirally arranged carpels above numerous spirally arranged stamens.

Left: Large blossom of the southern magnolia (Magnolia grandiflora). The numerous sepals and petals are called tepals because they are similar in size and shape. The conelike receptacle in the center is composed of numerous spirally arranged carpels and numerous spirally arranged stamens. The stamens have already fallen away in this photo, exposing the brown stalk (axis) of the receptacle. Right: Conelike receptacle bearing numerous follicles. Each follicle has split open and the seed has fallen out. Conelike fossils similar to magnolia receptacles have been discovered in ancient sedimentary strata, indicating that this is a very primitive plant family.

Conelike receptacle of Magnolia grandiflora bearing numerous follicles. At maturity (December in southern California), each follicle bears a bright red seed. The seeds often hang out of the individual follicles by their long, threadlike stalks (funiculi).

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