72 SIR J. LUBBOCK—PHYTOBIOLOGICAL OBSERVATIONS. 
apical tooth, that of Œ. biennis being subsessile, that of Œ. ma- 
erantha very shortly petiolate. In (E. biennis the cotyledons 
appear simply to expand; they retain the broadly ovate form, 
with the minute apical tooth, but become gradually petiolate *. 
But though there is thus no marked constriction in (Enothera 
biennis between the original cotyledon and the new growth, the 
latter is marked by a slight tooth at the point of junction, but 
still more by having the margin ciliate with incurved hairs, and 
a midrib with curved lateral veins; in both which characters it 
resembles the true leaf. 
In Œ. Lamarckiana the cotyledons resemble those of Œ. 
biennis, but become rather more truncate at the base and more 
pointed at the apex; so that their form is more wedge-like or 
obeuneate. The apical tooth is not apparent, and the basal foliar 
portion of the cotyledon is distinguishable only by the midrib and 
the fringe of incurved hairs, there being neither a notch nor a 
tooth to mark the transition. 
In @. rosea the cotyledons resemble those of (E. biennis; 
but they have not the apical tooth, and the margin is not ciliate. 
In this species, however, the leaves themselves are distantly 
dentate, and the petioles are slightly pubescent but not hairy ab 
the margin; they are broadly ovate, obtuse, entire, and with 
petioles nearly equalling their own length. 
In Enothera linearis the cotyledons much resemble those of 
Œ. rosea, as also do those of Œ. pumila, Œ. serotina, and E. 
glauca, which latter, however, are ultimately cuneate at the 
base. 
To the same group of species, so far as the cotyledons are 
concerned, belongs also Œ. fruticosa. 
Enothera micrantha affords us a case very similar to Œ. bis- 
torta. The cotyledons immediately after germination (fig. 151) 
are, as already mentioned, oval-obtuse with a slightly prominent 
apical tooth, and very shortly petiolate; they soon become 
(fig. 152) spatulate, with an oval entire tip representing the 
original cotyledon, and a linear cuneate portion at the base, 
generally with a minute tooth on each side, and glandular . 
pubescence. In the third stage (fig. 153) they arelinear, re- 
sembling a stout handle to the broad ovate cotyledon, which 
has grown to about twice its original length and retains the 
* The arrangement of the cotyledons in the seed is variable: sometimes they 
are flat, sometimes involute. 
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