i68 
G. R. WIELAND 
Fig. 5. Cycadeoidea Dartoni seed 
in longitudinal section (radial to 
cone). I, I, termination of tubular 
celled cortex forming supporting 
basal cup to erect seed; 2, 2, the 
blow-off layer of radially set cells 
enveloping shoulder region much as 
the magnolia flowers is illusory, and he 
finds reasons for dicotyl derivation from the 
Gnetalesin: (i) the inflorescence, (2) floral 
morphology, (3) the details of sporogenesis, 
(4) fertilization, (5) embryogeny, (6) or- 
ganization of vessels in the wood, (7) broad 
rays, (8) companion cells in the bast, (9) 
habit and foliage, and (10) the dicotyledon- 
ous embryo. 
This is a sweeping summation, so regard- 
less of plant 'history that it would scarcely 
be expected to come from a paleobotanist. 
It does not set aside the possibility that the 
gnetaleans have merely paralleled the angio- 
sperms, as Seward and others have sug- 
gested . In any sense of finality in evidence, 
the validity of these points falls one by one. 
It will not do to compare the gnetaleans 
of today with the cycadeoids of the Trias. 
And what the gnetaleans were like in the 
Jura, the fertile time of angiosperm origin, 
is too uncertain. Neither can 20,000 to 
30,000 species be safely hypothesized for 
them as in the case of the cycadeoids. 
They can not be hypothesized out of hand 
on vague leaf characters. Commenting, 
then, seriatim on these ''points": It must 
be insisted that taking the greatly reduced 
Wielandiella flower of the Trias, nothing is 
simpler than to infer related forms with 
few-seeded flowers grouped spirally. It is 
a mistake to attach all significance to this 
mere sporophyll emplacement, or to relation 
between singly borne and inflorescent flow- 
ers. This might arise late or early. Nextly, 
it is wrong from even the purely histologic 
standpoint to assume that the Gnetum 
flower of the Jurassic was more reduced than 
cycadeoid flowers. Besides, though sepa- 
in Gnetum Gnemon; 3,3, lateral and 
shoulder development of the radially celled stony layer which is prominently four- or five- 
ribbed ; 4, a thinner schlerenchyma of small elongate cells or fibrous hypoderm; 5» main 
inner parenchymatous layer; n, the nucellus arising from the chalazal base containing 
central supply of numerous small scalariform tracheids; m, megaspore membrane; di- 
cotyledonous and exalbuminous embryo filling the nucellar cavity. Length of seed four 
millimeters. 
