ARKIV Fön BOTANIK. 



BAND 17. N:o 11. 



Notes on the cytology of Ananas sativns Lindl. 

 and the origin of its parthenocarpy. 



By 

 O. HEILBORN. 



With 7 figures in the text. 

 Communicated September 14th by G. Lagerheim and O. Rosenberg. 



In his book on crossing as the cause of apogamy in the 

 vegetable kingdom Ernst (1918) also devotes a chapter to 

 a discussion of the origin of parthenocarpy. He there ex- 

 presses the opinion that parthenocarpic cultivated plants 

 most probably must be of hybrid origin, as the degeneration 

 phenomena, found in their ovules and anthers, show a certain 

 resemblance to those of sterile hybrids. Conclusions, drawn 

 from such comparisons, are, however, rather uncertain, espe- 

 cially if they are not completed Vjy cytological studies on 

 chromosome numbers and reduction division. Of parthf no- 

 carpic species and races, only the edible bananas. Musa 

 sapientum, have as yet been studied cytolopically from this 

 point of view (Tischler 1910, d'Angremond 1914) as well as 

 some species of Carica, recently investigated by the present 

 writer (Heilborn 1921). Consequently our knowledge of 

 this problem is still very incomplete, especially as the works 

 just mentioned do not arrive at quite conclusive results. 

 Further studies are thus desirable. 



Ananas sahvus is an almost totally parthenocarpic species. 

 According to Webber (1900) it is very seldom that a perfect 

 seed is found in the fruits that reach the American markets 



Arhiv för holanih. lid 17. X:o 11. 1 



