54 THE OPHIOGLOSSALES 



known it will be found that a large foot is present in the embryo, as it is in the 

 Marattiaceae and the other Ophioglossaceas, and the apparent absence of this foot 

 in the older embryo is due to the root apex being formed deep in the central tissue 

 of the embryo, as it is in the Marattiaceae and in Ophioglossum moluccanum, and 

 pushing its way downward through the foot, which thus becomes indistinguishable 

 from the outer tissue of the root. 



Except for the absence of the foot the organs of the older embryo oi B. obliquum 

 show the same relative positions as those of B. virginianum, and, as in the latter, 

 the first leaf is apparently a functional green leaf which appears above the surface 

 of the earth. 



THE EMBRYO OF HELMINTHOSTACHYS. 



The embryogeny of Helminthostachys, the third genus of the Ophioglossaceae, 

 is unfortunately very incompletely known. Lang (Lang 1), to whom we owe the 

 only published account of the gametophyte and young sporophyte, was unable to 

 secure any young embryos and only very scanty material of the later stages. Lang 

 says of the youngest forms which he found (Lang 1, page 40): 



"The large hemispherical foot is deeply inserted in the tissue of the prothallium. 

 The upper portion of the embryo had burst through the covering also of the latter; 

 in it can be distinguished the primary root — the first leaf — and (covered over by 

 the sheath of the first leaf) the depressed apex of the stem. The position of the 

 organs is thus essentially similar to what is found in Botrychtum virginianum." 



Lang's material was collected in the Barrawa Resei"ve Forest, in Ceylon, and 

 in February 1906 I visited the same locality and collected a large number of young 

 sporophytes, many of which were still connected with the gametophyte; but none 

 of the gametophytes were young enough to show young embryos. As we have 

 already suggested, it seems very probable that the gametophyte of Helminth- 

 ostachys, like that oi Ophioglossum moluccanum, is annual and produces normally a 

 single sporophyte, after which it perishes. The development of the gametophyte is 

 probably dependent upon the annual inundation of the forest, and this perhaps 

 accounts for the fact that all of the young sporophytes were of about the same age. 



The youngest specimen which I found is shown in fig. 10. The petiole of the 

 leaf was about i centimeter in length, and at the tip the minute lamina, strongly 

 bent over like the young leaves oi Botrychtum. virginianum, could be seen, showing 

 the three lobes which characterize the fully expanded leaf. The cotyledon is rudi- 

 mentary in Helminthostachys, the "cotyledon" described by Lang being really the 

 second leaf. At the base, but separated from the root by a short internode, is 

 a swelling which marks the position of the apical bud, inclosed within the hollow 

 sheath at the base of the petiole. The root at this stage is still quite short, the first 

 green leaf seeming to be more precocious than in Botrychium and thus resembling 

 Ophioglossum moluccanum. 



As the leaf grows the lamina expands and is seen to be ternate in form. Very 

 often the two lateral lobes are of unequal size and show that the ternate form is due 

 to an unequal dichotomy, such as is common in many ferns in the early leaves, which 

 are transitional between the dichotomously divided cotyledon and the pinnate 

 leaves of the older sporophyte. The ultimate divisions of the veins, as in Botrych- 

 ium, are dichotomous.* 



* In a recent note (Lang 2) it is stated that a suspensor also occurs in HelminihoUachys. 



