Sentence:  At Hortus Bulborum you will find heirloom <WSD>narcissi</WSD> that date back at least to the 15th century and famous old tulips like 'Duc van Tol' (1595) and its sports. 
Meaning of the word marked with <WSD> tags:  Any of several bulbous flowering plants, of the genus "Narcissus", having white or yellow cup- or trumpet-shaped flowers, notably the daffodil