IOWA ACADEMY OP SCIENCE 
27 
sion, however, is incorrect, as Ewart states, because the long-lived seeds, 
and many of them have starchy material, are found in the Legiiminoseac. 
Some years ago one of us^^ made a study of the seeds of leguminous 
genera found in Gray’s Manual. It was found that nearly all of the 
seeds studied had a cuticle, especially pronounced in the Mimoseae, 
Caesalpinieae and most of the Papilionaceae. Many of the seeds are 
known to have an especially long vitality. 
It has long been known that some of the seeds of the Leyuminosae. 
especially clover, will not germinate the same season that they are 
planted. The best seeds of the red clover are the purple, these are also 
the hardest. Hiltner'^ was the first to show that when hard seeds of 
clover are treated with sulphuric acid they germinate after treatment. 
Jarzymowski,^^ Ewart and others have shown that such treatment hastens 
germination. Bergetheil and Day"^ and Miss White"" have shown that 
the cuticle is impermeable to water. 
It has long been known that certain paired seeds like the cocklebur 
will not germinate the same season. The cocklebur seeds were first 
carefully studied by Arthur"® who found that generally the germination 
of one seed is delayed although both may germinate the same season. 
Nobbe and Ilanlein’s observation on some weed seeds show the same 
facts. 
AN EXPERIMENT WITH SOME IOWA WTEED SEEDS. 
In 1906 an experiment was started wdth 130 different kinds of weed 
seeds. The seeds were mature so far as we could tell. They were 
placed in paper packages and left in the laboratory. Plantings were 
made as follows : November, December, January, March and April. 
A second set of samples of the same weed seeds of 130 species was placed 
in linen sacks, covered with earth and buried six inches in the soil. 
They were thus subject to the varying conditions of an Iowa winter. 
These seeds were carefully removed in April and planted with the other 
samples for comparison. The tables are too long to produce in this con- 
^^Pammel, L. H. Trans. Acad. Sci., St. Louis, 9.89. 
^^Arch. aus d. biol. Abt. f. Land u. Porst. Wiss. 3:30, 1902. 
^Tnaug. Diss. Halle. 1905. 
Ann. of Bot. 21: Jan., 1907. 
"’Proc. Royal Soc. Victoria. 21:203. 
-®Proc. Soc. Prom. Agrl. Sci. 16:70. 
-‘Ueber die Resistenz von Samen genen die aussern Factoren der Keimung 
Landw. Versuchs. Stat. 20:63. Ueber die Keimkraft von Unkrautsamen. 
Landw. Versuchs Stat. 25:465. 
