220 
simple, spirally arranged leaves. They usually produced two kinds 
of spores—small (microspores) and large (megaspores), in cones. 
This phenomenon is called heierospory (unlike spores). Although 
the majority had attained the stature of large trees in later Paleo- 
zoic times, their existing relatives are herbaceous perennials. 
The fossil forms of which restorations are shown constitute at 
least three distinct families of the order Lepidodendrales, all of 
which are very prominent elements in Paleozoic floras. Prolo- 
lepidodendron, or Archaeosigillaria as it is sometimes called, is a 
wide ranging type of the upper Devonian and earlier Carbon- 
iferous. Quite a few species have been described, the most com- 
plete of which was from the upper Devonian, near Naples, N.Y. 
A fine life sized restoration in the State Museum at Albany is the 
basis of the present picture. The dichotomously branched trunk, 
six or eight inches in diameter and about twenty feet tall, is covered 
with leaf sears, irregular near the butt, and like those of a ribbed 
Sigillaria above these. Higher up, the vertical ribs die out, anc 
spirally arranged boisters with rhomboidal leaf scars, resembling 
those of Lepidodendron, make their appearance. The persistent, 
lax, pointed leaves are a little over an inch long and much like those 
O [ Both odé nd} Oil, 
Protole pidodeudron appears to have been a synthetic type, closely 
related to the common stock from which both the sigillarias anc 
ary 
fame 
the lepidodendrons were derived. 
+ 
ated forms, the ear 
— 
1e second type—Bothrodendron—really includes a number of 
— 
re ier often called Cyclostigma. They were 
larger than Protolepidodendron, with small remote leaf scars, usu- 
ally without bolsters. The leaves were small, simple, and more or 
less persistent. The trunk had a thinner zone of secondary wood, 
and the cortex was less differentiated than in the lepidodendrons 
and sigillarias. Several sorts of cones have been considered to 
belong to Bothrodendron—some like the ordinary cones of the 
later lepidodendrons, and others lacking the radial elongation so 
characteristic of these. 
— 
The sigillarias and lepidodendrons of the later Paleozoic em- 
brace a wide variety of forms, most of which were arborescent 
and some were over 125 feet tall with trunks over 6 feet in diam- 
eter. It would require too great space to even sketch the anatomi- 
