Sensimilla does not refer to a particular breed or strain of plant. Any female marijuana plant which is prevented from becoming fertilized will produce flowers without seeds. This contributes to a higher THC content in the harvest because none of the buds have had a chance to turn into seeds. This also contributes to the quality and rarity of Sensimilla product because an unfertilized sensi-yeilding plant is unable to reproduce (until fertilized).
The term "Sensimilla" is broken down to translate in Spanish as "without seeds" (sin semilla), however the term was coined and popularized in the context of marijuana culture by California growing regions. (which have strong Spanish/Mexican cultural influence)
that's why I do not snort the coke I only burn the Ganja."