90 STAMENS. 



Orchids, on the other hand, the number of pollen-sacs is reduced to two, a number 

 which remains unaltered at maturity. 



The pollen-sacs in the anthers of the Mimoseae are very curiously formed. In 

 the anthers of Acacia, Alhizzia, Calliandra, and Inga, there are eight spherical 

 chambers in which pollen is produced, whilst in Parkia we find longitudinal rows 

 of lenticular cavities in which balls of pollen lie embedded. The anthers also 

 of the Rhizophoreae show several longitudinal rows of such chambers, amounting 

 in all to as many as thirty. The anthers of the Mistletoe {Viscum, fig. 214^^) 

 contain as many as forty to fifty pollen-chambers. In the majority of the Laurels 

 (Lauracese) each anther is divided into four cavities, which stand in pairs, one 

 above the other. As a rule, all four open towards that side by which insects 

 visiting the flower for honey have to pass. 



Many marked variations in the form of the anther are due to the relative 

 dimensions of connective and pollen-sacs. Thus in the majority of RanunculacesB, 

 Magnoliaceae, Nymphaeacese, and Papaveraceae, the con- 

 nective is broad, the pollen-sacs forming only a narrow 

 rim to the anther (cf. fig. 214^''). In the Skull-cap 

 {Scutellaria), Calamint (Galamintha), Thyme (Thymus), 

 and many other Labiates, as also in several Rosaceee 

 (Rosa, Agrimonia, &c.), the connective has the form of 

 a three- to six-sided mass of tissue in which are embedded 

 Fig. 216— Curved anthers in the the sphciical or egg- shaped pollcn-sacs. Such anthers 



flower of Phyllantkus Cy- n .-, ^ -, . ,>i n-jii ii i 



danWiera (after Baiiion). frequently resemble an insects head with two lateral eyes. 



It is not always possible to distinguish the limits of con- 

 nective and filament, the whole stamen resembling a truncate column or anvil 

 (figs. 216 ^^ and 216 ^2). 



Sometimes the connective assumes the form of a bar or lever running 

 transversely to the filament, to which it is attached by a movable joint. This 

 is notably the case in certain species of Salvia, to be described hereafter. Such 

 a connective moves very readily upon its fulcrum. In many Liliaceas (e.g. Tulips, 

 Lilies, and Crown Imperials) and several Gentians (Qentiana ciliata, nana, &c.), 

 the anther is united with the filament by an extremely delicate joint, so that 

 the slightest touch sets it in vibration (versatile anthers). As examples of bulky 

 pollen-sacs and much reduced connective, Mirabilis Jalapa (fig. 214 ^s) and Solanum 

 Lyoopersicum (fig. 216 2) may be quoted as examples. 



It stands to reason that the character of the anther, indeed of the whole stamen, 

 is correlated with the form of the pollen-sacs. All possible stages occur between 

 globular and egg-shaped, and between egg-shaped and linear pollen-sacs. The 

 drawings of sixty-four different stamens in figs. 214 and 216 give a good idea 

 of the variety in this respect. Very curious are the curved anthers of Phyllantkus 

 Cyclanthera (fig. 215), and those of Acalypha, which resemble a ram's horns 

 (fig. 214^'); the same remark applies to the undulating anthers of many 

 Cucurbitaceae, of which those of Bryonia dioica may serve as an example 



