Flora in the ground cover is regulated, at least in part, by the canopy cover; hence different associations of pinyon-juniper woodland and each of the stands mentioned above have different plants, or a different distribution of the same kinds of plants, in their ground cover.
Units A, B, E, and parts of D and G in the western third of the grid are in pinyon-juniper woodland (Fig. 5). A relatively pure understory of _Poa fendleriana_ (muttongrass), is typical of such woodland on the middle parts of the mesas. Woodland on the western third of the grid differs somewhat in that, when the area occupied by each plant is considered, _Artemisia tridentata_ is codominant there with _Poa fendleriana_. As far as individual plants are concerned, _Poa_ far outnumbers _Artemisia_. The next most abundant plants in the ground cover are _Solidago petradoria_ (rock goldenrod), _Chrysothamnus depressus_ (dwarf rabbitbrush), and _Penstemon linarioides_ (penstemon), in that order.
In unit E there is a large depression, about 200 by 60 feet, created by removal of soil (Fig. 8). _Artemisia nova_ grows there, and pioneering plants adapted to early stages of succession are present.
A zone of woodland, where _Artemisia nova_ replaces _A. tridentata_ as an understory codominant with _Poa fendleriana_, borders the pinyon-juniper-muttongrass community to the east. The next most abundant plants in the ground cover are _Solidago petradoria_, _Penstemon linarioides_ and _Comandra umbellata_ (bastard toadflax). _Koeleria cristata_ (Junegrass) is as abundant as _Comandra_, but probably is less important as a source of food for mice.
A small strip of the pinyon-juniper-muttongrass community with an understory of _Artemisia nova_ and _Purshia tridentata_ (bitterbrush) adjoins the above area to the east (Figs. 5-8). _Solidago petradoria_, _Balsamorrhiza sagittata_ (balsamroot), and _Comandra umbellata_ are the three most abundant plants in the ground cover. The terrain slopes eastward from this zone into a large drainage.
[Illustration: FIG. 5: Diagram showing the major associations of understory and overstory vegetation in a trapping grid located south of Far View Ruins, Mesa Verde National Park, Colorado.]