202. 
4. Heads subtended by spiny leafy bracts; 
peduncles short, leafy. 
5. Principal cauline leaves deeply pinnatifid 
into linear-lanceolate lobes...........++.. C. discolor 
5. Principal cauline leaves entire or shallowly 
lobed. Expected (C. altissimum). 
4. Heads not subtended by leafy bracts; 
peduncles long, with scattered and reduced 
bracts. Expected (C. virginianum). 
1. Flowers dioecious. (Also, leaves green both sides).... C. arvense 
Cirsium vulgare (Savi) Tenore Bull Thistle 
Ivy Neck. One station: edge of cornfield on Cheston Peninsula, 
near head of Cheston Creek estuary. Hectare 4755. Associate species: 
Datura stramonium, Abutilon theophrasti. Higman 1220. 
C. discolor (Muhl.) Spreng. Thistle 
Java Farm. Moderately abundant along old entrance road south 
of main building area, and in grassy parts of old fields. Hectares 2590, 
3500, 3504. Associate species: Poa pratensis (dense turf), Asclepias 
syriaca, Apocynum cannabinum, Erigeron canadensis, Aster dumosus. 
Higman 44, 337. 
C. arvense (L.) Scop. Canadian Thistle 
Java Farm. One station: beside old entrance road just south of 
main building area. Hectare 3500. Associate species: Cirsium discolor, 
Asclepias syriaca, Verbascum thapsus, V. blattaris. Higman 888. 
Heliantheae 
1. Ray flowers absent. 
2. Shrub; salt marsh habitat; heads monoecious, the 
pistillate flowers 1 to 5, marginal, without 
corolla; the staminate flowers numerous, 
central, with lobed corolla....secsesesecesceeecees Iva 
2. Herbs; terrestrial habitat; heads dioecious, the 
pistillate ones clustered below spikes of staminate ones; 
pistillate heads 1- or 2-flowered; staminate heads 
5- to 20-flowered. 
