eee ee Ue RON ob tals.) be loN 9 
Flowering Dates of Local Plants 
By FLoyp A. SWINK 
Senior Naturalist, Cook County Forest Preserve District 
THIS SURVEY REPRESENTS the results of data taken on several hundred field 
trips in the Chicago area during the 17-year period from 1942 to 1958, in- 
clusive. The area covered includes the counties of Walworth and Kenosha 
in Wisconsin; Lake, McHenry, Du Page, Cook, Will, Kane, and Kankakee in 
Illinois; Lake, Porter, and La Porte in Indiana; Berrien in Michigan. 
No attempt has been made to determine average blooming dates, but 
rather the very earliest and latest recorded for each species at any time 
during the 17-year survey period. None of the records was made from cul- 
tivated plants, but always from wild specimens in the field. Undoubtedly 
most of the dates cited will eventually be extended by future workers, espe- 
cially during the years having a very early spring or very late autumn. 
Data has been omitted concerning the more inconspicuous flowers, such 
as grasses, sedges, rushes, and catkin-bearing trees and shrubs. Also those 
species have been omitted which, due to their rarity, have been observed 
in bloom only a few times. Scientific nomenclature is in accordance with 
Gray’s Manual of Botany (eighth edition). No attempt has been made to 
include varieties and forms. 
It is a frequent phenomenon for some early blooming species to bloom 
again in the autumn, skipping a good portion of the summer. In such cases 
the normal flowering dates are given, and the fact of a possible recurrent 
autumnal blooming period is indicated by an asterisk before the latest date 
shown. Box 31, Willow Springs, Illinois 
COMMON NAME SCIENTIFIC NAME EARLIEST LATEST 
Wdder’s= Tongue, White--- | Erythronium albidum_—-----~--~-~- Marchi3 02s" May 10 
Adder’s Tongue, Yellow__________ Erythronium americanum__—-----. mNgorenl Usha Nile ny 1B 
ERIS SITY 1) Vee cas ee Sas 8 Agrimonia gryposepala____------~ daly de Ren YR 
DNC Ete e fees eee cae es IVeUC CO Om SOL it ae er A ibeovea es oe ees Oct, 8 
ANRDUGS). URVOYO a - 22 5 oe ad Dy Oe a re Heuchera richardsoniu—-—--.-—---- Wine Ges aici Zt 
IV SSUTMe OARy ete ee IBerieCrOCm tn CONG = a ee diane ij Aug. 25 
Amaranthon Oreeping= —— 228 Amaranthus graecizans———_—_--_---~- Ul yaa ee Oct. 8 
AmMemonenm HalsemRuG.s)=. = Isopyrum biternatum_—__________= ‘wore! Nase e es WER BI? 
Anemone, prairies. -----_--_--. Anemone canadensig_=———-.._=---- IRIs af INES, We 
PSTICMONCHAIVUGs seen te SF, Anemonella thalictroides______----~ Marche 2 S22 =5 June 13 
PmierMmOnere Dalles eh ey Anemone virginiana—_——->——---_-- June eee ATO 1G 
ETO OTIO WN VVLOO Cee ee es Anemone quinquefolia________----~ Fay ayer Por We eee See May 30 
Jaxingeg ethers). Gana: | ae aa ae a Angelica atropurpurea________--—-. MIEKY. DOE Ss on. June 19 
Arrowhead. Conimon = 2 SCLOLELC LOLOL OlI = ee ee ee dhwlky Aja Sa Sept. 8 
Arrowhead, Grass-Leaved________. SOQUEL MOTI Ue Caer ee June ts eee Sept. 29 
Arrow-Wood, Maple-Leaved______- Viburnum acerifolium——_—______-__ June pea July 4 
PASTOR PAPIG KI Veer ee Xanthoxylum americanum_—————-~— Posenh WG} IER? Bal 
PXSH mV iterate ee ee PEClCGMETtlOUMt Oe oe ee Maya 292=2=2=— Junens? 
ENS SETGT AVE De Asparagus officinalis____________-. Mayall 2s Sept. 16 
Pen hodelmbcises. suseeso 08. Tio felaia Oli NOs@ ee Anan: eke se, (OYAe, Gl 
Aster, Arrow-Leaved_____________ ASLCTAESOOLLCLTOIUUS Set eee Auge 7A eas IN OWviemelar 
Stet ee Bist OD ee ee AsterewimnDelaluus san eee Aug sae Oct. 6 
asters Max-eaved 222-2 oo Aster linarifolius.-_—__________— AMvoteg OXY na oe, (OX, VA 
Aster, Great-Leaved_.____________ Aster macrophyllus________-_--—-- AUG se Ghee Oct. 9 
AStereevLarshmuer aeons LK aL MS ITED LC ee JiMlyuc Osea ae Nov. 2 
Aster, iNew) Pnelands2. 2s... Aster novae-angliae__________-__-_- uly 2 oes Oct. 27 
A stereh1Gew bULLONe =) ae FAISLOTIEO LINO SUS See ee ee Awol oes Octs 22 
