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IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
green, 2-5mm. long, l-2mm. wide, spreading or like scales on the 
stem. 
Sporangia single in the axils of ordinary or slightly modified 
lvs., usually forming a terminal strobilus or conelike group. 
Family 1. LycopodiaceaE Club Moss Family 
Lvs. spirally arranged, many ranked. Spores all alike. 
Lycopodium Club moss; ground pine. 
(Lycos, wolf; pous, foot; from a fancied resemblance) 
Characters of the family. 
1. L. lucidulum Shining L. 
Lvs. all alike, nearly at right angles to stem, sometimes a group 
bearing sporangia at base, finely toothed at apex. 
Cool shaded rocks, very rare here. 
Eldora 
Nfd. to Minn., Ia., and S. C. 
July 
Note: Other species of Lycopodium are commonly imported at Christ- 
mas time for wreaths under the name of ground pine. Druggists usually 
have spores of these plants under the name of Lycopodium powder. The 
related genus Selaginella. is often seen as a flat-sprayed delicate greenhouse 
plant, with two kinds of spores, large and small. Two species 2-5cm. tall 
grow wild in neighboring regions. In the coal period, the predecessors of 
these plants grew to the size of trees, with heavy woody trunks and roots. 
Their fossil prints occur in Iowa coal, and are known as Stigmaria, Sigil- 
laria, and Lepidodendron. 
Order 2. EquisETaeES 
Stems jointed, with a sheathlike whorl of united minute lvs. at 
each node. Spores green, cottony, in conelike heads at the ends 
of stems. 
Note: In the coal period, plants resembling Bquisetum grew to the size 
of trees, with woody stems and cambial growth. Their huge jointed stems, 
2-4 dm. thick, are sometimes found in coal. 
Family 8. EquisETaceaE Horsetail Family. 
Characters of the Order. 
Bquisetum Horsetail 
(Equus, horse; seta, bristle) 
Scales of cone hexagonal, with 6 or 7 sporangia beneath. Spores 
with 4 slender, broad tipped “elaters” (threads) which coil and 
uncoil when moist or dry. Stems hollow, grooved, with large 
air canals in the cortex, and a small one in each vascular bundle. 
Note: The elaters are extremely sensitive to moisture; the breath 
breathed over them causes great activity, especially as seen with a micro- 
scope. These plants are evidently the reduced herbaceous remnants of a 
once large and wide-spread family, the Calamites and Sphenophyllales. 
1. Stems delicate, soft, annual; some of them much branched 
1. Stems stiff, evergreen, little if at all branched 
2 
3 
