Identification key to the genera of bamboos from the Serra do Cachimbo, Eastern Amazon, Brazil

1. Leaves not differentiated into culm leaves and foliage leaves; leaves without an outer ligule..........................................................2

- Culm leaves and foliage leaves clearly distinct; foliage leaves bearing an outer ligule ....................................................................6

2. Leaf sheaths with fimbriae at the apex; synflorescence spiciform, comprising a series of whorls with five staminate spikelets surrounding a central sessile female spikelet .......................................................................................................................... Pariana

- Leaf sheaths without fimbriae at the apex; synflorescence paniculate or racemose, without whorls of spikelets.............................3

3. Culms 6–40 cm tall, sprawling or decumbent; leaf blades 0.4–1.5 cm long, ovate-triangular or elliptic............................ Raddiella

- Culms 2–4 m tall, erect, rarely clambering; leaf blades 17–32 cm long, oblong-lanceolate, ovate-lanceolate or lanceolate............4

4. Female spikelets 7.3–32 mm long, pedicels clavate to subclavate............................................................................................. Olyra

- Female spikelets 3–4 mm long, pedicels filiform ..............................................................................................................................5

5. Anthecium foveolate (with small pits) only at the apex................................................................................................... Parodiolyra

- Anthecium foveolate (with small pits) over the entire surface............................................................................................... Taquara

6. Infra- and supranodal band of white trichomes present on the culms; midnerve of foliage leaves prominent..................................7

- Infra- and supranodal band of white trichomes absent on the culms (sometimes present in Merostachys); midnerve of foliage leaves not prominent......................................................................................................................................................................................8

7. Blades of culm leaves reflexed, narrower than the sheath summit; branch complement without thorns ...................... Eremocaulon

- Blades of culm leaves erect, confluent with sheath summit; branch complement with thorns............................................... Guadua

8. Branch complement consisting of 3-many branches borne on a promontory; culm leaf blades erect....................... Arthrostylidium

- Branch complement apsidate (fan-shaped); culm leaf blades horizontal or reflexed ........................................................................9

9. Culm leaves dimorphic, terminal culm leaves (apex of the culm) with blades distinctly developed in comparison with those of the midculm; culm leaf sheaths with “ruffle-like” fused fimbriae persistent...................................................................... Actinocladum

- Culm leaves not clearly differentiated along the culm, blades similar in size; culm leaf sheaths with fimbriae free, caducous......... ......................................................................................................................................................................................... Merostachys