78 IOWA ACADEMY OF SCIENCES. 



The most striking difference is the lower temperature at the surface of the earth. 

 The observations on the following plants may be of interest : 



September 16: Corn, although young, was not affected close to thermometer. 

 On creek bottom one mile from college leaves were frozen. Twitch grass (Panicum 

 copillare) near the thermometer was not frozen. Common bean {Phaseolus vul- 

 garis) leaves frozen near the thermometer. Pussly {Portulaca oleracea) affected m 

 garden. Cucumbers {Citmis sativus) also affected. Cultivated balsams (Impatiens 

 balsomina) also affected. Frost on October 8th and £th entirely killed garden beans; 

 tomatoes seriously affected. Four o'clock [Mirabalis jalapa), balsam, corn, beans, 

 cucumbers, squashes, pumpkins, melons, tomatoes, pussly. Pigweed [Amarantiis 

 hliloides, Zinia coleiis. Morning Glory {Ipomtva purpurea), Unicorn plant {Mar- 

 tipiia proboscidea) seriously affected. 



Of the partially affected I will enumerate a few: Red Clover (Trifoliunt pra- 

 iense), Dolichos lablab, Castor Oil Bean {Ricinns communis), Cotton {Gossi/pium) 

 herbaceum) and Cassia mari/Jandica. 



Not affected at all: Phlox drumniondii, Mexican poppy [Argemone mex'tcaua). 

 Sage {Salvia pratensis). Bachelor's Button \Centaurea ci/anus). Golden Rod [Soli- 

 dngo rigida). Aster {Aster multiporus), Scabios {Scabiosa atropurpurea), Artichoke 

 {Helianthus tuberosiis), Beet [Beta vulgaris), Fleabane [Erigeron annuus). Tansy 

 {Tanaceium vulgare). 



Up to this time frost had in no way affected the flowering of Phlox drmnmondii. 

 Salvia piratensis, Melissa, Argemone ine.vlcana, Eschscholtzia californica, Borage 

 {Borrago officinalis), Collinsia bicolor, Erigeron annimm. One of the curious 

 things in connection with some plants is that in plants like the Castor Oil bean 

 only the lower leaves were frost bitten, while the others were still green and fresh 

 on October 18th. 



The following plants were entirely killed between October 18th and November, 

 4th: Dolichos lablab, Ipomoea purpurea, Datura urightii, Gossi/piam herbaceum, 

 Qaamoclit vulgaris, Phaseolas tnultiflorus. Hibiscus trionum. Calendula officinalis. 



Partially affected: Ricinus communis, Helianthus debilis, Borrago officinalis, 

 Trifolium pratense, T. incarnaium, Polanisia graveolens, Soja hispida. 



On October 24th the following were slightly affected: Cosmos, Solamim ni- 

 grum, Chri/santhetim corinarium, Argemone mexicana. Cassia marglandica ^ 

 Trifolium pratense, Eschscholtzia californica, Melilotus officinale. 



Not affected by frost on 23d and 24th: Euphorbia eg pari ssias. Pelargonium 

 zonale, Medicago sativa, Sgniphgtum officinale, Solidago rigida, S. canadensis. 

 Aster novw-anglicB, Scrophularia nodosa, var. marijlandica, Erodium cicutaria. 

 Phlox drnmmondii, Dipsacus sijlvestris, Chrgsanthemum indicum, Silphium laci- 

 natum, Scabiosa atropurpurea, Nepeta cafaria, Acalypha virginica, Marrubium vul- 

 gare, Potentilla not regica, Tartacetum vulgare, Centanrea cyanus, Iris versicolor, 

 Triosteum perfoliatum, Poteriiim sanguisorba, Collinsia bicolor, Arctium major, 

 Saponaria officinalis. Beta vulgaris, Daucus carota, Brassica campestris, Salvia 

 pratensis, Scabiosa atropurpurea, Nepeta cataria, Fragaria virginiana. 



The leaves of trees of the following species were affected somewhat: Prunus 

 americana, Eleagnus angustifoUa, Acer saccharinum, Betula alba, Populus alba, 

 P. tremula. 



Leaves of shrubbery plants killed by frost on October 25: Ulmns fnlva, Ulmus 

 americana, Acer negundo, Vitis riparia, V. labruscce, various cultivated forms, of 

 Prunus cerasus, P. avium, Fraximis viridis, Pyrus malus. 



Not affected: Prunus persica, Berberis vulgaris, B.thumbergii, Pyrus com- 

 munis, Ligustrum vulgare. 



