124 MORPHOLOGY, OR COMPARATIVE ANATOMY. 



In the Lauracese (fig. 233) we find either two or four little lids of 

 this kind, opening the two or four cells of the anthers. 



If the anther he considered the equivalent of a leaf with infolded 

 margins, then the groove "between the two lohes would represent the 

 margins of the leaf; but there is reason to suppose that no such infolding 

 really occurs, but that two pollen-sacs are formed on either side of the 

 connective without any involution of the margin. 



Stamens of Gymnosperms. The stamens of the Gymnospermia 

 present remarkable conditions, which require separate notice. 



Among the Coniferee (see that order) the stamens of Pinus constitute the 

 entire male flowers, and are conjoined into male cones, each anther forming 

 a scale of the cone ; they are bract-like plates, bearing on the lower face two 

 parallel anther-lobes (bursting longitudinally or irregularly), beyond 

 which the connective extends more or less as a scale-like process. In 

 Cupressus the form of the anther is excentrically peltate, the lobes, three 

 or four in cumber, standing under the overhanging connective ; and it is 

 similar in Juniperus and Tliuja. In Taxus the peltate connective is more 

 symmetrical, and radiately grooved above, having from three to eight 

 vertical anther-lobes beneath : some authors regard this as a group of 

 monadelphous stamens. 



In the Cycadaceas (for illustration see that order), where the anthers are 

 scattered in large numbers over the lower face of the scales of the male 

 cones, they occur mostly in the form of groups of four simple anther-lobes, 

 with longitudinal dehiscence and arranged in the form of a cross. These 

 are mostly described as parcels of unilocular anthers. 



Number of the Stamens. The stamens, taken collectively, 

 present a number of characters, which have received technical 

 names. The number of stamens in a flower is indicated by the 

 terms mon-androus, di-androus, &c. ; when more than twelve exist, 

 the term poly-androus is employed. Upon the number of the 

 stamens the Linnean classification was partly founded. When 

 the number of the stamens is equal to, or some multiple of, the 

 number of petals in the corolla &c., the flower is isostemonous ; 

 when the number is different (as in Scrophulariacese &c.) the flower 

 is anisostemonous. "When there is one whorl of stamens in the 

 normal position, the term haplostemonous is employed; diploste- 

 monous is used where there are two whorls, and obdiplostemonous 

 where there are two rows of stamens, the outer superposed to the 

 petals. 



Relative length. Two cases of inequality of length of the 

 filaments are distinctly named, viz. the didynamous condition 

 (figs. 234 & 235), when there are two pairs of stamens, one pair 

 longer than the other, characteristic of many irregular Monope- 

 talous flowers (Labiatae, Scrophulariaceae, &c.) ; and tetradynamous 



