Sentence:  Its <WSD>bipennate</WSD> leaves are composed of a slightly straightened general petiole, of four partial petioles, situated, two at the extremity of the proceeding, and convergent, two a little lower, and growing almost at right angles; each of them bearing more than twenty pairs of small horizontal petioles. 
Meaning of the word marked with <WSD> tags:  Bipinnate (pinnate and having a pinnate leaflet).