Aspikelet, inbotany, describes the typical arrangement of the inflorescences ofgrasses,sedges and some othermonocots.
Each spikelet has one or moreflorets.[1]: 12 The spikelets are further grouped intopanicles orspikes. The part of the spikelet that bears the florets is called therachilla.[1]: 13
InPoaceae, the grassfamily, a spikelet consists of two (or sometimes fewer)bracts at the base, calledglumes, followed by one or more florets.[1]: 13 A floret consists of the flower surrounded by two bracts, one external (thelemma) and one internal (thepalea). Theperianth is reduced to two scales, calledlodicules,[1]: 11 that expand and contract to spread the lemma and palea; these are generally interpreted to be modified sepals.
The flowers are usuallyhermaphroditic —maize being an important exception — and mainlyanemophilous or wind-pollinated, although insects occasionally play a role.[2]
Lemma is aphytomorphological term referring to a part of the spikelet. It is the lowermost of twochaff-likebracts enclosing the grassfloret. The lemma often bears a long bristle called anawn, and may be similar in form to theglumes, which are chaffy bracts at the base of each spikelet. It is usually interpreted as a bract but it has also been interpreted as one remnant (theabaxial) of the three members of outerperianthwhorl (thepalea may represent the other two members, having been joined together).
The lemmas' shape, their number of veins, whether they are awned or not, and the presence or absence of hairs are particularly importantcharacters in grasstaxonomy.
Palea, inPoaceae, refers to one of the bract-likeorgans in the spikelet.
The palea is the uppermost of the two chaff-like bracts that enclose the grass floret (the other being thelemma). It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs. This has led to suggestions that it may be what remains of the grass sepals (outer perianth whorl): specifically the two adaxial members of the three membered whorl typical ofmonocots. The third member may be absent or it may be represented by the lemma, according to different botanical interpretations.
The perianth interpretation of the palea is supported by the expression ofMADS-box genes in this organ during development, as is the case in sepals ofeudicot plants.[3]
Alodicule is the structure that consists of between one and three small scales at the base of the ovary in a grass flower that represent thecorolla, believed to be a rudimentaryperianth. The swelling of the lodicules forces apart the flower'sbracts, exposing the flower's reproductive organs.
Authority control databases: National |
|---|