On the True Nature of the Cretaceous Plant 
Ophioglossum granulatum, Heer. 
BY 
MARIE C. STOPES, D.Sc., Ph.D. 
With two Figures in the Text. 
/~XBJECT of the Paper: —-To show that the Cretaceous impressions 
V -S known as Ophioglossum granulatum, Heer, are wrongly attributed to 
this genus: that the American specimens are male cones of Pinus : that the 
specific identity of these with the Greenland specimens is uncertain : and, 
finally, to urge a simple method of distinguishing well-founded from 
problematical determinations, such as would be afforded by the use of 
Gothic type for the specific names of the latter. 
The only Ophioglossum included in Knowlton’s 1 useful list of the 
Cretaceous and Tertiary plants of North America, and indeed, so far as 
I am aware, the only recorded Cretaceous species of Ophioglossum , naturally 
attracted my attention when I was examining the Cretaceous plants for 
a larger work on which I am engaged. The Ophioglossums are of interest 
both from the exceptional nature of the living plants, and from the fact 
that we have almost no material from which to reconstruct their geological 
history. 
In 1883 Heer 2 described the family Ophioglossaceae as being repre- 
sented in the Patoot (Cretaceous) beds by a new species, O. granulatum. 
The materials on which. this determination was based were one or two 
incomplete, slender aments, in which were oval, closely packed granules, 
which he held to be sporangia, and which he thought were much like those 
of O . vulgatum in size and shape. No leaves were found. The species was 
defined as ‘ O. spica fertili elongata, sporangiis distichis, ovalibus granulatis, 
i§ mm. longis \ 
Reference to Heer’s Fig. 8 , PI. LVII, will convince any one of the 
extremely problematic nature of the specimen, and of the danger that must 
lie in determining it from its external features. Notwithstanding this, how- 
1 Knowlton, U.S. Geol. Surv. Bull. No. 152, 1898. 
2 Heer, * Flora foss. Arctica.’ Die foss. Flora Gronlands, pt. ii, 1883. See p. 8 and PI. LVII, 
Figs. 8, 9. 
[Annals of Botany, Vol. XXV. No. C. October, 1911.3 
