Ruderal (roadside) communities occur in areas of disturbances such as along roadsides, trails, parking lots, etc.  These communities, which occur along the Poly Canyon Road, are subjected to ongoing or past disturbances (e. g., vehicle activities, mountain bikes, mowing, etc.).  In these disturbed areas, ruderal assemblages of native and introduced weedy species become established.  A band of ruderal vegetation borders the Poly Canyon Road, and similar assemblages of plants occur along some of the other roads and trails in the areas around Poly Canyon.  The components of the ruderal community vary from place to place and with the nature of the disturbance.  Most of the species that occur in these disturbed areas are various annual grasses and forbs of Eurasian origin, many of which also occur in the grasslands.  There are also a few natives that are adapted to grow in these disturbed sites such as telegraph weed, and turkey mullein.

Ruderal communities are often successional in nature, covering the ground for a few years after a disturbance has taken place, and eventually giving way to the native and climax communities of the area when the disturbance factor is removed.  Some of the introduced weeds, however, often maintain a position in the community as succession takes place, and the community may take years to or in some cases never return to its original state.  Some of the common plants in the ruderal community along Poly Canyon Road are listed below.

Common Plants of Poly Canyon Ruderal Community:

Carduus pycnocephaluss (italian thistle)
Chamomilla suaveolens (pineapple weed)
Conium maculatum (poison hemlock)
Erodium botrys (stokbill filaree)
Foeniculum vulgare (fennel)
Marrubium vulgare (horehound)
Medicago polymorpha (bur-clover)
Mellilotus indica (yellow sweet-clover)
Nicotiana glauca (tree tobacco)
Plantago spp. (plantain)
Sonchus oleraceus (common sow thistle)
 

In addition to the ruderal or roadside plants, several exotic trees and shrubs have been planted in Poly Canyon.  The most common is Eucalyptus globulus (blue gum) which occurs in small clusters as well as as individuals.  These trees are typically taller than any of the trees native to the creek area and tower over the other plants of the area. As a result, they shade the ground and litter the soil surface with fallen branches, leaves, fruits and bark.  Fog-drip and rainwater passing through the leaves and branches carry dissolved chemicals that add to the substances leached from the fallen litter producing an allelopathic (growth inhibiting) effect on understory vegetation.  The net result is that few other plant species are able to grow in the understory of blue gum stands.  Consequently, the understory is often sparse if present at all.  Eucalyptus trees are Australian natives but are well adapted to the environmental conditions of the central California coast area and grow fast and tall.  In some areas the trees appear to have become naturalized and are reproducing and maintaining themselves successfully.

There are many other exotic trees and shrubs found in Poly Canyon in addition to Eucalyptus.  These represent another form of human influenced communities.    The common ones are listed below.

Acacia baileyana	acacia
Acacia longifolia	wattle
Casuarina sp.	beefwood
Cotoneaster pannosa	cotoneaster
Eucalyptus globulus	blue gum
Eucalyptus spp.	eucalyptus
Juglans  sp.	walnut
Melaleuca armillaris	melaleuca
Olea europea	olive
Phoenix canariensis	date palm
Pistacia atlantica	pistacio
Prunus spp.	almond, cherry, peach
Schinus molle	pepper tree
Ulmus parvifolia	elm