bract

Within-shrub differences among bractless and control half-plants regarding the vigor of the progeny were significant (and in the expected direction if bracts increased seed quality; question 5) only in two out of five cases.

Since there were fewer pollen tubes within styles of bractless shrubs, however, and because tube number has a number of implications on progeny development (e.g., through microgametophyte competition, Hill and Lord 1986, Snow 1986, Mulcahy et al.