Written by Merel Dagher (PEACE Advisor)
Which of the following are heterosporous? Select all that apply.
a. Ferns
b. Moss
c. Cycadophyta
d. Monocots
e. Lycophytes
a. Ferns
b. Moss
c. Cycadophyta
d. Monocots
e. Lycophytes
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The correct answers are c, d, and e, though not all lycophytes are heterosporous (meaning they possess microspores and megaspores); Selaginella is a type of lycophyte that is heterosporous. All seed-bearing plants are heterosporous (so gymnosperms, which include Cycadophyta, and angiosperms, which can be split into monocots and eudicots). Ferns and moss are homosporous (the spores are indistinguishable in gender). For homosporous spore production: sporangium on sporophyll leads to a single spore type which leads to a bisexual gametophyte which produces eggs and sperm. For heterosporous spore production: megasporangium on megasporophyll make megaspores via meiosis which results in the female gametophyte which produces eggs; microsporangium on microsporophyll make microspores which yield the male gametophyte through mitosis which produces sperm.