CONIFERM. .-Q 



remain for a long time adjacent and united, the pro-embryo producing only a small- 

 celled rudiment of an embryo at its apex (Fig. 324, B, C) ; while in the Abietinecs 

 (Abies, Pinus) and Cupressineae (Thuja, Juniperus) the elongated cells of the pro- 

 embryo separate from one another, continue to grow in this condition, and each 

 forms the rudiment of an embryo at its apex^ (Fig. 325, IV, v, III). By this means 

 several embryos can be produced from one embryonic vesicle ; the number within 

 a single endosperm being increased by the simultaneous fertilisation of several 

 archegonia. Polyembryony, which is rare among Angiosperms, is thus the typical 

 condition among Conifers and generally among Gymnosperms, but only in the very 

 earliest stage; for usually only one of the rudiments developes into a vigorous 

 embryo, such as has already been described. During its development the endo- 

 sperm also continues to grow vigorously; its cells become filled with reserves of 

 food-material (fat and albuminoids) ; the embryo-sac which surrounds it grows at the 

 same time, and finally supplants the tissue of the nucleus, the tissue of the integu- 

 ment hardening at the same time into the testa. In Salisburia, how^ever, an outer 

 strong layer of tissue forms the pulpy envelope which causes the seed to resemble 

 a drupe. The elongated cells of the pro-embryo usually disappear during these 

 processes, but according to Schacht are permanent in Larix. 



During the period that the seeds are ripening, the carpels and the placentae 

 also continue to grow and to undergo changes in texture. In Taxus a red aril 

 which afterwards becomes pulpy grows round the ripening seed (Fig. 318 w); in 

 Podocarpus the part of the floral axis that bears the scales and the seeds, and which 

 was already considerably swollen, becomes fleshy ; in Juniperus and Sabina the 

 carpels themselves form the blue 'berry' which envelopes the seeds: in most other 

 Cupressincoe the carpels grow, close up laterally and become woody ; and the same 

 occurs in those Abietineae which are without bracts (in respect to Cunninghamia, 

 vide supra) ; while in Pinus, Abies, Cedrus, and Larix, it is the placental scales 

 which after fertilisation grow vigorously, outstripping in their growth the true carpels 

 (bracts), become woody, and form the mature cone. In all these cases (except 

 Podocarpus, Salisburia, and Taxus), the seed is closely and firmly enclosed during 

 ripening by the carpels or placental scales ; it ripens within the fruit, the parts of 

 which do not again separate or become detached in order to allow of the escape 

 of the seeds until they are completely ripe (as in Ahies pedinata). 



• So long as we are still in doubt as to the nature of the female flowers of various 

 genera, the systematic arrangement of the Coniferae can only be considered as provi- 

 sional ; Endlicher (Synopsis Coniferarum, 1847) distinguishes the following families:— 



First Family. Cupressineae. Leaves, including those of the flowers, opposite or 

 verticillate (in Division e single) ; flowers moncecious or dioecious ; stamens terminating 

 in a shield-like expansion bearing pollen-sacs in twos or threes or larger numbers ; 

 female flower consisting of alternate \vhorls of carpels, bearing at their base or on their 

 inner surface two or a larger number of erect ovules (in Juniperus comtnunis the ovules 



^ See in addition Schacht, Lehrhuch der Anat. u. Phys. vol. II, p. 462. According to Pfitzer (/. c.) 

 the young rudiment of the embryo has at first an apical cell, which however soon disappears ; in the 

 Abietine^ the mode of formation of the embryo is from the first like that in Angiosperms. 



