The Bambusoideae is a subfamily of the true grassfamilyPoaceae, and is characterized by having 3 stigmas and are mostly tree-like. However, there are uncertainties at practically every taxonomic level within the Bambusoideae, and different types of data (floral morphology, vegetative structures, anatomy, and genetics) often result in support for differing relationships.
The Bambusoideae generally consists of a distinct “core” group of genera, the woody bamboos (Bambuseae) and an associated group of genera of questionable affinity, the herbaceous bamboos (Olyreae). The bambusoid taxa have long been considered the most “primitive” grasses, mostly because of the presence of bracteate, indeterminate inflorescences, “pseudospikelets,” and flowers with three lodicules, six stamens, and three stigmas.
Flora distribution map of the Poaceae subfamily Bambusoideae.
In a recent study  DNA sequences for the chloroplast gene ndhF were analyzed to address phylogenetic relationships among the major lineages of the Poaceae. They found that two tribes of neotropical herbaceous bamboo tribes, the Streptochaeteae and Anomochloeae, are resolved as the most basal clade within the grass family, confirming the hypothesis that elements within the Bambusoideae sensu lato are basal within the Poaceae, and also showing that the Bambusoideae s.l. is polyphyletic. A recent study which analyzed the phylogenetic relationships within the Bambusoideae using rp116 intron sequence data from chloroplast DNA was able to further resolve some of the uncertainties remaining in Clark et al.’s (1995) analysis. Kelchner and Clark’s (1997) analysis resolved a Bambusoideae clade with two monophyletic groups: the Bambuseae (woody bamboos) and the Olyreae/Parianeae (herbaceous bamboos).
Within the Bambuseae two clades were recovered corresponding to temperate and tropical woody bamboos, and the tropical taxa were even further divided into New World and Old World clades. The distinct lineages produced strongly correspond with geographic divisions, with major clades representing the New World herbaceous species (Olyreae/Parianeae), New World tropical woody bamboos, Old World tropical woody bamboos, and North temperate woody bamboos (all Bambuseae).
Bambusoideae is divided into two groups:
It has 13 tribes, as following:
This group is also separated into subfamily Oryzaceae.
^Kelchner, SA, LG Clark. 1997. Molecular Evolution and Phylogenetic Utility of the Chloroplast rpl16 Intron in Chusquea and the Bambusoideae (Poaceae). Molecular Phylogenetics and Evolution 8(3): 385-397.