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Cucurbit Genetics Cooperative Report 10:83 (article 43) 1987

Electrophoretic Classification of Cucurbita Cultivars

J. T. Puchalski

Botanical Garden of the Polish Academy of Sciences, Warsaw, Poland

R. W. Robinson

Horticultural Sciences Department, New York State Agricultural Experiment Station, Geneva, NY

Cucurbita mixta was not recognized as a distinct species until 1930. Previously, members of this species were considered to be C. moschata. Although separated by partial sterility barriers, the two species are very similar in morphology. The taxonomic key feature, of the peduncle of C. mixta being corky and not flared at its attachment to the fruit, is not always reliable for distinguishing the two species.

A more reliable method of classification is by electrophoresis, since C. moschata and C. mixta have distinct patterns for esterase, peroxidase, peptidase, acid phosphatase, and other isozymes. By means of isozyme analysis, we determined that some cultivars previously considered to be C. mixta are actually C. moschata.

The term cushaw, like that of pumpkin and squash, refers to fruit type and usage rather than to a taxonomic entity. Isozyme analysis revealed that each of these terms has been used for cultivars of more than one species of Cucurbita. 'Green Striped Cushaw' has isozymes of C. mixta, agreeing with the previous morphological classification by Cutler and Whitaker (2). 'White Cushaw' also was previously classified as C. mixta (2), but it had isozymes of C. moschata. 'Golden Cushaw' also had isozyme banding patterns characteristic of C. moschata. 'Tennessee Sweet Potato' has been reported (2) to be C. mixta, but the isozymes of the accession of this cultivar we tested were typical of C. moschata.

The Seminole Pumpkin, which has been cultivated for centuries by Indians in Florida (3), was identified by Bailey (1) and Erwin (3) as C. moschata, despite its peduncle being more typical of C. mixta than C. moschata (3). Its isozyme phenotype, although distinctive fr6m other T. moschata cultivars tested, is in agreement with the Seminole Pumpkin being C. moschata. The isozyme evidence does not support the theory (4) that 'Seminole' is derived from a cross between C. moschata and C. okeechobeensis. Fertile hybrids were easily obtained of 'Seminole' x 'Butternut', confirming that 'Seminole' is C. moschata.

Literature Cited

  1. Bailey, L. H. 1929. Addenda in volume II, particularly in relation to nomenclature. Gentes Herbarum 2(7):427-430.
  2. Cutler, H. C. and T. W. Whitaker. 1956. Cucurbita mixta, its classification and relationships. Bull. Torrey Bot. Club 83:253-260.
  3. Erwin, A. T. and E. P. Lana. 1956. The Seminole Pumpkin. Econ. Bot. 10:33- 57.
  4. Morton, J. F. 1975. The sturdy Seminole Pumpkin provides much food for thought. Florida State Hort. Soc. Proc. 88:137-142.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 16 October, 2009