receptacle [ ri-SEP-tuh-kuhl ] noun: the portion of the flower stalk (axis) upon which the floral parts are borne
hypanthium [ hi-PAN-thee-uhm, hahy- ] noun: a cup- or tube-shaped entity bearing the androecium, corolla and calyx on its rim and usually surrounding or enclosing all or part of the ovary
hypogynous [ hahy-POJ–uh-nuhs, hi- ] adjective: of a flower whose androecium, corolla, and calyx arise from the receptacle beneath the gynoecium
perigynous [ puh–RIJ–uh-nuhs ] adjective: of a flower whose androecium, corolla and calyx are borne on a hypanthium surrounding but not attached to the ovary
epigynous [ ih-PIJ–uh-nuhs ] adjective: of a flower whose androecium, corolla and calyx are attached to the top of the ovary
Central to the discussion of the terms above is a plant’s ovary, the portion of the gynoecium that bears the ovules, which become the seeds. The placement of the ovary is not only important in understanding the structure of a flower, but also in understanding the type of fruit a ripened ovary will become.
The receptacle, once called a thalamus, is the thickened part of the flower stalk (pedicel or peduncle) from which a flower grows. It is sometimes referred to as the floral axis as it bears the four floral whorls (calyx/sepals, corolla/petals, androecium/stamens, and gynoecium/carpels).
A flower, in which the androecium, petals, and sepals emerge from the receptacle below the gynoecium, is called hypogynous (the prefix ‘hypo” meaning under or beneath and “-gynous” referring to a plant’s female organ). Its ovary is referred to as superior. Examples of hypogynous flowers (and their fruit) include buttercup (achene), Solomon’s-seal (berry), tulip (loculicidal capsule), and those in the Brassicaceae, cabbage family, (silique).
Left to right: Hypogynous flower diagram, longitudinal section of Eurasian Solomon’s-seal, native large Solomon’s-seal.
[Note: The diagram labels = (a) androecium, (p) petals, (s) sepals, (r) receptacle, and (g) gynoecium.]
The hypanthium is sometimes referred to as a floral cup or floral tube or an enlarged floral receptacle. A perigynous (the prefix “peri” meaning surrounding) hypanthium connects the androecium, petals, and sepals to the floral base and is not associated with the gyneocium (Basso-Alves et al., 2017). In a perigynous flower, the bases of the androecium, petals, and sepals are fused to hypanthium tissue, which forms a cup around, but not attached to, a superior ovary. Examples include flowers of the genus Prunus, like peaches and plums, that produce drupes.
Left to right: Perigynous flower diagram, longitudinal section of a Prunus flower, American plum.
When the androecium, petals, and sepals lie above the ovary, the flower is epigynous (the prefix “epi” meaning upon or over) and the ovary is considered inferior. Although this may seem as straightforward as flowers with a superior ovary, the origin and development of the gynoecial hypanthium and the inferior ovary have been debated for over two centuries and have spawned numerous theories. Among them, two have prevailed.
The appendicular (aka Candollean or concrescence) theory posits the inferior ovary “is the result of concrescence [growing together] of all of the floral whorls” (Douglas, 1944). The bases of the androecium, petals, and sepals fuse to form a floral tube—the hypanthium—to which the inferior ovary wall adheres. The receptacular (aka axial) theory holds that the inferior ovary “is entirely axial, excepting for its apical covering” (Douglas, 1944). The ovary is enclosed in and united with the floral receptacle, thus the hypanthium is an axial cup. However, how the whorls fuse together and at what level result in many variations of epigyny (Sharawy, 2018). For example, an inferior ovary could be partly appendicular and partly receptacular or an ovary could be semi-inferior.
Ist Row (top to bottom): Epigynous flower diagram, longitudinal sections of a Bartlett pear flower and pome. 2nd Row (top to bottom): Daffodil flower section and loculicidal capsule. 3rd Row (top to bottom): Composite flower diagram and golden ragwort fading flowers and cypselae with pappi..
Studies of numerous plant families have shown that most epigynous flowers tend to be appendicular in nature (Costello and Motley, 2004). Epigynous flowers that are receptacular are less common and found in Rosa; Calycanthus; the Santalaceae, sandalwood family; possibly the Juglandaceae, walnut family (Douglas, 1944); and in the Cactaceae, cactus family (Costello and Motley, 2004). Examples of epigynous flowers (and their fruit) include pear (pome), narcissus (loculicidal capsule), and those in the Asteraceae, aster, daisy, composite, or sunflower family, (cypsela). Fruit formed from an inferior ovary may include other flower parts, such as the hypanthium (as seen in the pear above), petals, sepals (as seen in the form of pappi in the golden ragwort above), or bracts.
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References
Basso-Alves JP, Goldenberg R. Teixeira SP. 2017. The ontogenetic bases for variation in ovary position in Melastomataceae. American Journal of Botany. 104(8): 1142-1156. DOI: 10.3732/ajb.1700114
Berkeley E. 1953. MORPHOLOGICAL STUDIES IN THE CELASTRACEAE. Journal of the Elisha Mitchell Scientific Society. 69(2): 185–208.
Costello A and Motley TJ. 2004. The development of the superior ovary in Tetraplasandra (Araliaceae) †. American Journal of Botany. 91(5): 644-655. DOI: 10.3732/ajb.91.5.644.
Douglas GE. 1944. The Inferior Ovary. Botanical Review, 10(3): 125–186.
Olvera HF, Smets E, Vrijdaghs A. 2008. Floral and inflorescence morphology and ontogeny in Beta vulgaris, with special emphasis on the ovary position. Annals of Botany. 102(4):643-51. doi: 10.1093/aob/mcn140. Epub 2008 Aug 10. PMID: 18694878; PMCID: PMC2701786.
Reznicek AA, Voss EG, Walters BS. February 2011. Prunus. MICHIGAN FLORA ONLINE. University of Michigan. Web. (Accessed February 28, 2024).
Saburi W, Jr. Reato LR. de Godoy SAP. 2005. Floral venation patterns in Siphocampylus (Campanulaceae)†. American Journal of Botany. 92(5): 797-801. Doi: 10.3732/ajb.92.5.797.
Sharawy SM, Khalifa SF. 2018. The Nature of the Interior Ovary in Some Monocotyledonous Families. Journal of Plant Development. 25: 25-42. DOI: 10.33628/jpd.2018.25.1.25. ISSN 2065-3158 print / e-ISSN 2066-9917.
Simpson MG. 1998. Reversal in Ovary Position from Inferior to Superior in the Haemodoraceae: Evidence from Floral Ontogeny. International Journal of Plant Sciences. 159(3), 466–479.
Stover-Blackburn J, Editor. Fruit Anatomy. UCDavis Fruit & Nut Research & Information Center. © 2024 Regents of the University of California (accessed February 14, 2024).
Weakley AS, Ludwig JC, Townsend JF. 2012. Flora of Virginia. Botanical Research Institute of Texas. ISBN 10: 1889878383. ISBN 13: 9781889878386.