Of all the genera of woody bamboos described from America, only three have pseudospikelets—Atractantha, Elytrostachys, andGuadua.The former two have pseudospikelets with an elongated rachilla internode that precedes the floret, making it pedicellate; they also share a type of leaf anatomy that separates them from the latter. The two new genera herein described,CriciumaandEremocaulon, show most similarity to species ofGuadua, both in spikelet morphology and in leaf anatomy. The study of these new taxa has helped to clarify the limits of New World genera with pseudospikelets and strengthened the case for maintainingGuaduaas a genus distinct from its Old World counterpart,Bambusa.We are now able to discern a New World line of bamboos that includesCriciuma, Eremocaulon, andGuadua, separate from an Old World line that includesBambusa, Dendrocalamus, and several other genera.