July 2019
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Rhaponticum exaltatum is an endemic and threatened plant species from the Iberian peninsula, with a very fragmented distribution. However, little is known about its reproductive biology. The aims of this study are 1) to characterise the morphology of its seeds; 2) to compare the germination success of the three most representative populations (Cuevas del Valle, El Hornillo and Pinar de Hoyocasero (Ávila, Spain)); and 3) to evaluate the effect of different ex situ germinative methods in the species. We find morphological differences, both in size and weight, among the populations, showing intraspecific diversity. Taking into account all the methods to stimulate the germination, one of the populations (Cuevas del Valle) show the highest germinative success, although it is still low (18.7%). We find that the studied method that stimulates the most the germination of R.exaltatum seeds is the stratification at 5ºC during 4 months. However, the response to this method differ among populations, preferring different temperature for germination. This difference could be explained with the geographical situation of the populations, and their local adaptation led by different evolutionary history. Further research is needed to study the reason of the different response of the populations under same conditions.