Sentence:  At Hortus Bulborum you will find heirloom narcissi that date back at least to the 15th century and famous old tulips like 'Duc van Tol' (1595) and its <WSD>sports</WSD>. 
Meaning of the word marked with <WSD> tags:  A plant or an animal, or part of a plant or animal, which has some peculiarity not usually seen in the species; an abnormal variety or growth. The term encompasses both mutants and organisms with non-genetic developmental abnormalities such as birth defects.