THE MALE FERN DRTOPTERIS FILIX-MAS 



(2) Sex organs are imperfect or absent, the antheridia being usually functional but 

 the archegonia absent. 



(3) The central cushion of the prothallus remains thin, and at a very early age 

 (compared with the time needed for a sexual prothallus) the various organs of a new 

 sporophyte are produced directly from it (cf. Fig. 42 a and d). 



(4) The first leaf of an apogamously produced plant resembles the second or third 

 leaf of a sexual one, the very simple first leaf of the normal sporophyte being un- 

 represented (cf. Fig. 43 ^).* 



a b 



Fig. 43- 



Fig. 44. 



Fig. 43. Prothalli bearing young plants each with a leaf and a root expanded, a. Dryopteris Filix-mas 

 produced sexually, b. Triploid D. Borreri produced apogamously. Note the difference in the form 

 of the first leaf. Twice natural size. 



Fig. 44. A pinna of Dryopteris Borreri var. polydactyla Wills. Natural size. Formerly known as 

 D. 'pseudo-mas' var. polydactyla Wills, a classic horticultural monstrosity originally found wild as 

 a single specimen but preserved in cultivation on account of the curious forked apices. A very 

 similar specimen known in horticulture as var. polydactyla Dadds is illustrated in Fig. 195, p. 187; 

 var. Wills is diploid (see below), var. Dadds is triploid (see Chapter 11). 



(5) The good sporangia generally liberate only 32 large spores instead of the 64 of 

 normal ferns. In addition to 'good' sporangia, others with aborted spores in various 

 numbers can generally be found (see Chapter 8 for further details) . 



(6) In the ripening of the sporangia there are some characteristic aberrations affecting 

 the last (premeiotic) mitosis (for further details see Chapter 10). 



Apogamy, detected by one or all of these various criteria, has been found in every 

 plant examined bearing any of the D. Borreri morphological characteristics from over 

 twenty different locahties in the British Isles. In addition, I was fortunate in receiving 



* This character was first noticed by Stange (1887) at a very early stage in the history of apogamy. 



58 



