GYMNOSPERMAE. — C YCADEAE. 



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which reach the considerable size of a mature medium-sized plum before fertilisation ; 

 the ripe seed, the altered macrosporangium now containing the macrospore, has the 

 size and appearance of a middle-sized apple hanging naked on the carpel. The 

 numerous leaves of the male flowers that bear the microsporangia, the staminal leaves, 

 are much smaller, seven or eight centimetres in length and not divided, becoming 

 broader above from a narrower base and pointed; on their under side are sori of 

 many microsporangia ; the whole flower is from thirty to forty centimetres in length. 

 The male and female flowers of the other genera of the Cycadeae are not unlike 

 fir-cones in outward appearance ; 



on a short naked stalk rises like 



a spindle the comparatively slender 



floral axis bearing numerous closely 



crowded leaves with macrospo- 



rangia or microsporangia (Fig. 



247), and ending above in a naked 



apex which has ceased to grow 



(Fig. 247 U). The staminal leaves 



are small indeed in comparison 



with the foliage-leaves of the same 



plants, and yet they are about the 



largest and most massive to be 



found in Seed-plants; in Macro- 



zami'a, as in Cycas, they are from 



six to eight centimetres long and 



may be three centimetres broad ; 



they are narrow at the point of 



insertion, expand into a kind of 



lamina, and are simply acuminate, 



as in Macrozaviia, or divide into 



two hooked points, as in Ceralo- 



zami'a; or again the lower part is 



slender like a stalk and bears a 



shield-like expansion (Zamid). The 



staminal leaves of the Cycadeae 



are also distinguished from those 



of most other Seed-plants by their 



persistence; they become lignified 



and often very hard. The numerous 



microsporangia (pollen-sacs) on the 



under side of the staminal leaves are usually collected together into small groups of 



two to five sporangia each, resembling the sorus of the Ferns ; these in their turn 



form larger groups on the right and left side of the leaf. The pollen-sacs are round 



or ellipsoidal, usually about one millimetre in diameter, and are attached to the under 



side of the staminal leaf by a narrow base, which in Zamia spiralis according to 



Karsten becomes a stalk ; they open by a longitudinal fissure. 



The development of the microsporangia and of the leaves that bear them is most 



Fig. 246. A fertile leaf (carpel) of Cycas ret'olula about half the natural 

 ; f the lobes of the carpel which resembles a foliage leaf, sk ovules iji 

 place of the lower pinnae, sk' a ni^ re highly developed ovule. 



