acrogen
noun
ac·ro·gen
ˈa-krə-jən
plural -s
: a plant of the higher cryptogams predominant in the Carboniferous era including ferns, fern allies, mosses, and liverworts and distinguished by growth from a special cell or growing point compare thallogen, thallophyte
Word History
Etymology
acr- + -gen; from the growing point's being at the tip of the stem
First Known Use
1834, in the meaning defined above