380 CUCUBBITACEOUS PLANTS. Chap. X 



Spanish nuts, oblong and longitudinally striated in Cosford's, and 

 obtusely four-sided in the Downton Square nut. 



Cucurbitaceous plants. — These plants have been for a long period 

 the opprobrium of botanists; numerous varieties have been ranked 

 as species, and, what happens more rarely, forms which now must 

 be considered as species have been classed as varieties. Owing to 

 the admirable experimental researches of a distinguished botanist, 

 M. Naudin, 136 a flood of light has recently been thrown on this 

 group of plants. M. Naudin, during many years, observed and 

 experimented on above 1200 living specimens, collected from all 

 quarters of the world. Six species are now recognised in the genus 

 Cucurbita ; but three alone have been cultivated and concern us, 

 namely, C. maxima and pepo, which include all pumpkins, gourds, 

 squashes, and the vegetable marrow, and C. moschata. These three 

 species are not known in a wild state ; but Asa Gray 137 gives good 

 reason for believing that some pumpkins are natives of N. America. 



These three species are closely allied, and have the same general 

 habit, but their innumerable varieties can always be distinguished, 

 according to Naudin, by certain almost fixed characters ; and what 

 is still more important, when crossed they yield no seed, or only 

 sterile seed; whilst the varieties spontaneously intercross with the 

 utmost freedom. Naudin insists strongly (p. 15), that, though 

 these three species have varied greatly in many characters, yet it 

 has been in so closely an analogous manner that the varieties can 

 be arranged in almost parallel series, as we have seen with the 

 forms of wheat, with the two main races of the peach, and in other 

 cases. Though some of the varieties are inconstant in character, 

 yet others, when grown separately under uniform conditions of life, 

 are, as Naudin repeatedly (pp. 6, 16, 35) urges, " douees dune 

 stabilite presque comparable a celle des especes les mieux caracte- 

 risees.'* One variety, l'Orangin (pp. 43, 63), has such prepotency in 

 transmitting its character, that when crossed with other varieties a 

 vast majority of the seedlings come true. Naudin, referring (p. 47) 

 to C. pepo, says that its races " ne different des especes veritables 

 qu'en ce gu'elles peuvent s'allier les unes aux autres par voie 

 d'hybridite, sans que leur descendance perde la faculte de se 

 perpetuer." If we were to trust to external differences alone, and 

 give up the test of sterility, a multitude of species would have to 

 be formed out of the varieties of these three species of Cucurbita. 

 Many naturalists at the present day lay far too little stress, in my 

 opinion, on the test of sterility; yet it is not improbable that 

 distinct species of plants after a long course of cultivation and 

 variation may have their mutual sterility eliminated, as we have 

 every reason to believe has occurred with domesticated animals. 

 Nor, in the case of plants under cultivation, should we be justified 



186 ' Annales des Sc. Nat. Bot.' 4th m 'American Journ. of Science,' 



series, vol. vi. 1856, p. 5. 2nd ser. vol. xxiv. 1857, p. 442. 



