Companion sterile spikelets (presence)
     ----well-developed

Spikelets of many genera of the tribe Andropogoneae are borne in dissimilar pairs, one member of the pair being fertile (and often sessile) and the other pedicellate, sterile and smaller, these are termed companion sterile spikelets. This also includes isolated triads and barren pedicels. There are also companion sterile spikelets in a few other genera, but most genera do not have companion sterile spikelets.

spikelet: a unit of the inflorescence, usually consisting of two glumes and one or more florets (each with palea and lemma between which the flower is borne).

inflorescence: the group or arrangement in which spikelets are borne on a grass.

pedicel: the stalk of a flower.

Images: 1 2 3 4

Hordeum hystrix triad of spikelets
(pedicelled companion spikelets well-developed)
© Flora of Victoria pg 516

Germainia grandiflora inflorescence and spikelet pair
((pedicelled companion spikelet well-developed))
© Queensland Herbarium
by Will Smith

Each spikelet consists of a number of flowers or florets arranged alternately on either side of a central axis, the rhachilla, above two empty bracts, the glumes. 'Bract' is a general term for a much reduced leaf, particularly small leaves subtending flowers. A grass flower is enclosed by two bracts, the outer one on the side away from the axis termed the lemma and an inner bract named the palea. The bracts, together with the flower, make up the floret.