300 



GRAMINEAE 



1. rolls up upwards in dry air, enclosing the stomata completely and 

 checking transpiration ; the lower surface, which thus becomes the 

 outer, is covered with thick-walled cells and has no stomata. When 

 the air again becomes moist the 1 unrolls. 



The infl. is complex; the unit of infl. is not the individual fl. 

 but a spikelet, or small spike of fls. These are well seen in oats, 

 where they are arranged in a panicle; in wheat the spikelets are 

 sessile upon the main axis, forming a cpd. spike, usu. termed simply 

 a spike ; this is more clearly seen in rye-grass. Each of these 

 spikelets consists of one or more (usu. not more than 5) fls. one 

 above the other on opp. sides of a very short axis, the whole enclosed 

 in one or two or more larger leaves at the base of the axis, the 



inf. palea - 



inf. palea - 



- inf. palea 



- inf. palea 



- outer glume 



glumes. The first diagram gives a rough 

 representation of the construction of a 

 spikelet. The central line represents the 

 axis (supposed elongated), which bears 

 at the base usu. two leaves with nothing inner glume -j 

 in their axils; these are the glumes 



Above them stand one or more leaves, the inferior paleae, in whose 

 axils occur fls. (sometimes aborted). Upon the axis of the fl., opp. 

 to the inf. palea, stands another leaf, the superior palea. Between 

 the paleae the fl. itself is enclosed. The sup. palea, being upon the 

 same axis as the fl., is evidently its bracteole. Owing to the short- 

 ness of the floral axis, it appears to be in the axil of the inf. palea, or 

 even upon the main axis of the spikelet. Above the sup. palea are 

 two very small scales, the lodicules; 

 they are opp. to the sup. palea (1 in 

 fig.) and insignificant in size. They 

 are sometimes supposed to repres. 

 two of the three 1. of a reduced P, 

 but it seems more probable that they 

 really repres. a second bracteole and 

 that the fl. is perfectly naked. The 

 fl. itself has usu. 3 sta. with long 

 filaments and versatile anthers, and 

 i cpl. forming a i-loc. ovary, with 

 i basal erect anatr. ovule, and i 

 or more (usu. 2) stigmas, much 

 branched. This ovary has some- 

 times been regarded as formed of 

 > i cpl., but the suture of the post, 

 side of the ovary (cf. Prunus) seems 

 to point clearly to its being of i cpl. only. The two stigmas may 

 then be regarded as developments of the lat. parts of the cpl. whilst 

 the central part (which usu. forms the stigma) remains undeveloped ; 

 this also is the explanation of the two lodicules placed right and left 

 of the proper position for an upper bracteole. 



All the fls. in the spikelet are enclosed as a rule within the 

 glumes until ready to open. Then the glumes separate, and the 

 hygroscopic lodicules force apart the paleae of the fls. Most sp. 

 in Eur. are anemoph. and protog. ; the sta. grow very rapidly in 



b 



Floral diagram of a grass (after 

 Eichler). b, inferior palea; 

 v, superior palea ; 1, lodicule ; 

 St., stigma. 



