schizocarp [ SKIZ–uh-kahrp, SKIT-suh– ] noun: a dry compound fruit that, at maturity, divides into two or more mostly indehiscent one-seeded segments (carpels), which are dispersed individually
mericarp [ MER-i-kahrp ] noun: one of the carpels of a schizocarp
Schizocarp, from the Greek words skhizo meaning “division or split” and karpos meaning “fruit,” is a typically indehiscent fruit in which each carpel in a compound ovary separates at maturity mostly into a one-seeded, usually indehiscent segment called a mericarp.
Schizocarps vary widely in structure and appearance as seen in the examples below. Some experts have attempted to distinguish the different kinds of schizocarps, but because there is not agreement on terminology, they will not be discussed here.
- The fruit of the Apiaceae, the celery, carrot, or parsley family, is a schizocarp. This family is also known as the umbellifers since the Inflorescence, which distinguishes it, is an umbel. The flower is epigynous with a bicarpellary ovary that develops into a schizocarp with two indehiscent, one-seeded, usually five-ribbed mericarps that are united facially. At maturity, the mericarps separate with each suspended at the tip of a forking central axis.
Left to right: Foeniculum vulgare (fennel) umbels of flowers and shizocarps, Daucus carota (wild carrot, Queen Anne’s lace) umbels of flowers and schizocarps.
- In the Geraniaceae, the geranium family, schizocarps are distinctively long-beaked comprising the style at the top and five one-seeded mericarps inside the calyx at the base. At maturity, the mericarps separate, each taking from the style a strip that often remains attached at the tip of the beak. These awn-like strips are hygroscopic so that when they peel away moisture and humidity cause them to coil upward. Some mericarps may dehisce.
- In the Malvaceae, the mallow family, hollyhocks have a disk-shaped schizocarp enclosed by the calyx. The 15–40 two-celled, one-seeded mericarps form a ring and at maturity separate from the central axis.
Left to right: Geranium maculatum (wild geranium) flowers and schizocarps.
Left to right: Alcea rosea (common hollyhock) flowers and schizocarp.
Some fruits may be schizocarpic in nature, but are not uniformly referred to as schizocarps. As is the case with other fruit types, experts do not always agree on what to call the fruit of particular genera so different flora may vary in their descriptions as in the examples below.
- The Lamiaceae, the mint or sage family, has two types of fruits, drupes and what the Flora of Virginia calls schizocarps and The Families of Flowering Plants characterizes as “more or less” a schizocarp. This fruit is described as usually having four nutlets, each with a single achene, enclosed in a persistent calyx. Other flora may refer to these fruits as simply nutlets, but A Systematic Treatment of Fruit Types says that they are really four mericarps as the “bilobed carpel divides into two halves as it matures.”
- In describing the characteristics of the Sapindaceae, the soapberry family, the Flora of Virginia refers to one of its fruit types as schizocarps that split into “samaralike” segments. It goes on to describe the fruits of one of its genera, Acer (maple), as “double samaras,” which develop as a pair, connected at a central axis, and are separable at length, with each half having usually one seed and dispersing individually. Although maple fruit have the characteristics of schizocarps and are referred to as such in some botanical literature, the Flora of Virginia description of each Acer species, such as Acer rubrum (red maple), simply calls the fruits samaras, and this is the term that most of us commonly use.
- Loments (aka lomentums) are legumes that are constricted between the seeds. Some botanists describe this constriction as schizocarpic.
Left to right: Lamiaceae member Monarda fistulosa (wild bergamot) terminal head of bilabiate flowers and developing and mature schizocarps,
Left to right: Schizocarpic fruits of Acer rubrum (red maple) and Hedysarum sulphurescens (yellow sweetvetch).
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References
Michigan Flora Online. University of Michigan Herbarium. (accessed June 28, 2024).
Spjut RW. 2003–2015. A Systematic Treatment of Fruit Types. ©The World Botanical Associates
Radford AE, Ahles HE, Bell CR. 1983. Manual of the Vascular Flora of the Carolinas. The University of North Carolina Press.
Watson L, Dallwitz MJ. 1992 onwards. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Geraniaceae. Labiatae. Malvaceae. Papaveraceae. Sapindaceae. Umbelliferae. Version: 14th December 2000. (accessed June 28–30, 2024).
Weakley AS, Ludwig JC, Townsend JF. 2012. Flora of Virginia. Botanical Research Institute of Texas.