"Curtisii" is a botanical term, referring to a species of plant named after William Curtis, an 18th century English botanist. The spelling of this word can be explained using the International Phonetic Alphabet (IPA). The word starts with the /k/ sound, represented by the symbol [k]. The second syllable contains the sound /ɪ/ ([ɪ]), pronounced like the vowel sound in the word "sit." The final syllable is pronounced like the letter "i," represented by the symbol [i]. So, the word is spelled as "kuhr-tis-ee" in IPA.