HARPER: TRIP ON WARRIOR AND TOMBIGBEE RIVERS 119 
species which are unquestionably native in the vicinity, as proved 
by the manner of their occurrence in other habitats. There is no 
known way of distinguishing which are native and which are intro- 
duced species by local observation alone, so recourse must be had 
to the statements in botanical literature, and those unfortunately 
are sometimes conflicting. According to the latest and best 
information obtainable, however, the weeds observed on this trip 
might be classified roughly according to the origin as follows: 
(There will of course be room for some difference of opinion here, 
and further study of the behavior of these plants in other parts of 
this country and in the tropics is needed.) 
I. Species endemic to the Eastern United States, and occur- 
ring often in perfectly natural habitats, but also capable of 
flourishing in weedy places. 
Spermacoce glabra, Diodia virginiana, Conobea multifida, 
Ipomoea lacunosa, Acuan illinoense, Fimbristyis Vahli, Panicum 
virgatum, Paspalum mucronatum, Andropogon furcatus, 
2. Species supposed to be confined to the Eastern United 
States, but occurring almost solely in unnatural habitats. Some 
of these have perhaps never had suspicion cast upon them before, 
but they will bear watching.* 
Spilanthes repens, Xanthium sp., Diospyros virginiana, Euphor- 
bia humistrata (and perhaps one or two of its congeners which I 
could not identify with certainty), Acalypha virginica, Meibomia 
sp. (perhaps more than one), Glottidium vesicartum, Panicum 
proliferum. 
3. Species apparently native in the Eastern United States, like 
those in the first group, but occurring also in tropical America. 
Conoclinium coelestinum, Eupatorium serotinum, Tecoma radi- 
cans, Ammannia coccinea, Ampelopsis arborea, Commelina hirtella, 
Fimbristylis autumnalis, Eragrostis hypnotdes. 
4. Species common to the Eastern United States and the 
tropics, supposed by most writers to be native here, but chiefly 
confined to unnatural habitats, like those in the second group. 
Eclipta alba, Ambrosia trifida, Physalis angulata, Jussiaea 
decurrens, Euphorbia nutans, Sesbania macrocarpa, Cebatha Caro- 
*Bartram’s Oenothera grandiflora, whose rediscovery farther down this same 
river in 1904 created a mild sensation among botanists (see Vail, Torreya 5: 9, Io. 
1905), probably belongs to the same class. 
