G. ANTHROPOGENIC COMMUNITIES
floods, earthquakes, droughts, fires and volcanic
eruptions are natural factors which historically have
influenced the distribution and species composition
of plant communities. In fact, some communities are
adapted to periodic natural disruptions: chaparral
communities depend on fire for renewal, and some riparian
communities require periodic flooding. However, not
all disruptions are natural nor are native plant communities
adapted to or, much less, dependent on them for survival.
Communities which are born of the repeated disruption
of natural habitats by humans are called anthropogenic,
human-generated. Until just over 200 years ago, California
did not know intensive European-style agriculture
or mass urbanization. When Europeans came to California,
the population of Native Californians was approximately
300,000. Today there are almost 100 times as many
people. And if sheer numbers were not sufficient impact
on the natural resources, also "present human demands
on the environment are drastically different from
those of the past. Traditional technologies of original
California peoples were based on the philosophy of
resource conservation and renewal. Use of their sophisticated
technologies meant modest impact on the ecosystem.
In contrast, European technologies are based on an
agricultural economy that changes wildness to a homogeneous,
managed landscape. The diversity of native vegetation,
animals, and cultures is threatened by this philosophy
communities have arisen from two main types of disruption:
agricultural (pastoral and agrestal) and urban (e.g.,
roadsides, trails, and empty lots). The plants that
grow in these areas are primarily Mediterranean species
that have been introduced intentionally (as crops,
forage, or ornamentals) or accidentally (in ballast,
animal feed, clothing, animal droppings, fur, hooves,
etc.). They are invasive weedy plants that are dependent
on disturbed land for their establishment. The term
"weed" is applied generally to plants that grow where
humans do not want them. In other words, a weed is
a relative thing: one person's flower garden is another's
weed patch. However, specialists agree that weeds
have certain characteristics shared by both native
and introduced species. "Herbert Baker, a botanist
at the University of California in Berkeley, once
concocted a list of traits that the ideal weed would
possess. No single weed has all of those traits or
we would be ankle-deep in that species. Baker's list
of traits for a successful weed includes fast growth
rate, early maturity and reproduction, an abundant
production of seeds, a prostrate habit, fragile stems,
the capacity for wind- or self-pollination, tolerance
of full sun, and seeds capable of long-term dormancy
in soil. These traits are most easily combined in
small, annual, herbaceous plants." Of the 5,867 plant
species in California, approximately 1,416 species
are endemic to California, and 1,023 others have been
introduced and survive in the wild. Although some
species occurring in anthropogenic communities are
natives, most plants dominating these communities
communities have developed on lands, primarily grasslands,
savannas, and oak woodlands, used for the grazing
of domestic livestock - cows, sheep, and goats. Dominant
species of these communities in Poly Canyon include
Italian thistle (Carduus pycnocephalus) which
is common in some places as a dense, spiny, impenetrable
mass under coast live oaks. On the site that was once
the Goldtrees' dairy, milk thistle (Silybum marianum)
and perennial mustard (Hirschfeldia incana)
dominate now. These communities occur adjacent to
riparian, coastal live oak woodland, coastal scrub,
chaparral, and rock outcrop communities. Pastoral
communities are more fully discussed as non-native
annual grasslands in the Grasslands section above.
Agrestal communities develop on cultivated lands,
not of concern in Poly Canyon. Ruderal communities
occur along roads and trails. Plant growth in these
communities is influenced not only by the usual climatic,
geologic, and topographic factors, but also by other
factors such as soil quality. The extreme compaction
of soils that occurs at roadsides decreases the aeration
of the soils, the penetration of water into the soils,
and the diversity and number of soil-inhabiting creatures
whose presence would counteract and even remedy the
effects of soil compaction. Root development and penetration
is more challenging under such conditions. Soil compaction
also increases water runoff and erosion. With increased
erosion, the organic layers of soil and nutrients
are lost. Another factor that impacts ruderal species
is pollution both by vehicle engines and pedestrian
litter. The dust that cars, trucks, bicycles, and
pedestrians kick up is another serious pollutant.
It settles on leaves lowering the amount of sunlight
received by the plants for photosynthesis. Also, it
covers the pores on plant surfaces thus altering the
processes of evapotranspiration.
unique example of an anthropogenic community is found
around the Poly Canyon landfill. There one can find
the following assortment of plants: Canary Island
date palm (Phoenix canariensis), tree tobacco
(Nicotiana glauca), Eucalyptus spp., Pinus
spp., pampas grass (Cortaderia jubata), cocklebur
(Xanthium strumarium), poison hemlock (Conium
maculatum), royal apricot (Prunus armeniaca),
almond (Prunus dulcis), and peach (Prunus
persica), to name a few. In that small area, all
of the continents except Antarctica are represented
by one or more of their native plants.
Poly Canyon, ruderal communities are dominated primarily
Scarlet pimpernel (Anagallis arvensis, Primulaceae)
*Slender wild oat (Avena barbata, Poaceae)
*Wild oat (Avena fatua, Poaceae)
Black mustard (Brassica nigra, Brassicaceae)
*Ripgut grass (Bromus diabdrus, Poaceae)
Italian thistle (Carduus pycnocephalus, Asteraceae)
Pineapple weed, rayless chamomile (Chamomilla
Bull thistle (Cirsium vulgare, Asteraceae)
Poison hemlock (Conium maculatum, Apiaceae)
*Storksbill filaree (Erodium botrys, Geraniaceae)
*Redstem filaree (Erodium cicutarium, Geraniaceae)
Fennel, sweet fennel (Foeniculum vulgare,
Perennial mustard (Hirschfeldia incana, Brassicaceae)
*Foxtail (Hordeum murinum, Poaceae)
*Italian ryegrass (Lolium multiflorum, Poaceae)
Horehound (Marrubium vulgare, Lamiaceae)
California burclover (Medicago polymorpha,
Sourclover (Melilotus indica, Fabaceae)
Tree tobacco (Nicotiana glauca, Solanaceae)
Bermuda buttercup (Oxalis pes-caprae, Oxalidaceae)
Bristly ox-tongue (Picris echioides, Asteraceae)
English plantain (Plantago lanceolata, Plantaginaceae)
Windmill pink (Silene gallica, Caryophyllaceae)
Milk thistle (Silybum marianum, Asteraceae)
Prickly sow-thistle (Sonchus asper, Asteraceae)
Common sow-thistle (Sonchus oleraceus, Asteraceae)
Chickweed (Stellaria media, Caryophyllaceae)
of these plants follow.
pimpernel (Anagallis arvensis, Primulaceae)
This is a 5- to 40-cm. (2- to 16-inch), low,
spreading annual. Its square stems bear opposite,
ovate leaves. The 7- to 11-mm. (1/4- to 1/2-inch)
rotate flowers are salmon-colored and have a
dark purple spot at the center. They bloom from
February through October. The fruit is a spherical
capsule. Scarlet pimpernel is native to Eurasia.
is Greek meaning "to delight in again," probably
because the flowers open each time they are
touched by the sun. Arvensis means "of
Chumash use this as a poultice for sores and
to bathe for eczema and ringworm.
wild oat (Avena barbata, Poaceae)
oat (Avena fatua, Poaceae)
mustard (Brassica nigra, Brassicaceae)
This is a 4- to 20-dm. (11/2- to 61/2-foot)
plus, erect, branching annual. It has a basal
rosette of pinnately lobed, finely toothed leaves,
as well as similar leaves along the stems. Bright
yellow, four-petalled flowers bloom at the branch
tips from March through July. The fruit is a
narrow, 1- to 2-cm. (1/2- to 1-inch) capsule
with a round beak. Black mustard is native to
is Latin for "cabbage." Nigra means "black,"
referring to the color of the seeds.
thistle (Carduus pycnocephalus, Asteraceae)
This hairy thistle is an annual. It has 2- to
20-dm. (1/2- to 61/2-foot) stems. It has alternate,
spiny-toothed, pinnately lobed basal leaves
with winged petioles. There are some similar,
but smaller and sessile cauline leaves as well.
Two to five heads of tubular florets are borne
together in a cluster at the end of the main
stem and branches. The tubular florets are pink-purple.
The fruit is a tiny golden to brown achene with
a pappus of barbed bristles. Italian thistle
is native to the Mediterranean region.
is the ancient Latin name. Pycnocephalus
means "thorny head."
weed, rayless chamomile (Chamomilla suaveolens,
Asteraceae) This is a 10- to 30-cm. (4- to 12-inch)
sweetly aromatic annual. Its leaves are twice
to three times pinnately lobed. They are small,
under 5 cm. (2 inches), and are bright green.
The inflorescence is a 1-cm. (1/2-inch) diameter
cone of miniscule yellow tubular florets. The
fruit is a cylindric, ribbed achene.The plant
is native to northeast Asia and northwest North
derivation of the generic name is unknown. Suaveolens
is the Spanish word for chamomile. Early Californians
made an infusion of it to drink to alleviate
stomach pains and nervousness; to induce perspiration;
to reduce pain, cramps, colic; to suppress menstruation;
for problems of the liver and in childbirth;
to treat catarrh (either a common cold or an
inflammation of the mucous membranes) and dysentery.
A poultice of manzanilla was used to
reduce inflammation. Now it is drunk as a tea
to soothe nervousness and indigestion.
thistle (Cirsium vulgare, Asteraceae)
This is a 3- to 20-dm. (2- to 5-foot) stout,
hairy biennial. Its lanceolate, lobed leaves
form a basal rosette. The leaf margins are spiny.
Leaves along the stem are armed with spiny teeth
and covered on the upper surface with short
prickles. The inflorescence is a spiny-bracted
head of purplish-red disk florets that bloom
from March through September. The fruit is an
achene with a pappus of plumose bristles. The
plant is native to Eurasia.
comes from the Greek kivsion, a kind
of thistle. Vulgare means "common."
hemlock (Conium maculatum, Apiaceae)
This is a 5- to 30-dm. (2- to 10-foot) branching
biennial. It has smooth, stout stems that are
green with purplish markings. The large leaves
are finely dissected, feathery-like. The inflorescence
is a compound umbel of white flowers that bloom
from May through July. The fruits are oval schizocarps
with wavy ribs. Poison hemlock is native to
Eurasia. All parts of this plant are TOXIC
is the ancient Greek name for "hemlock." Maculatum
means "spotted" and refers to the markings on
the stem and petioles.
filaree (Erodium botrys, Geraniaceae)
filaree (Erodium cicutarium, Geraniaceae)
sweet fennel (Foeniculum vulgare,
Apiaceae) This is a 1- to 2-m. (3- to 6-foot)
plus, stout, erect, glabrous perennial. The
stems are green, streaked, and branching. The
leaves are a deep, bright green and are finely
dissected (feathery). They are very aromatic
(smelling like licorice or anise). The inflorescence
is a compound umbel of small yellow flowers
that bloom from May through September. The fruits
are oblong, ribbed schizocarps. Fennel is native
to the Mediterranean region.
is Latin for "hay." Vulgare means "common."
seeds, stems, and leaves of hinojo (in
Spanish) are used as culinary herbs. The seeds
and roots are infused as a digestive aid (carminative
mustard (Hirschfeldia incana, Brassicaceae)
This is a biennial or perennial. It has 2- to
10-dm. (8- to 40- inch) stems. Its pinnately
lobed leaves are in a basal rosette flat on
the ground, with some along the stems. The flowers
have four pale yellow to white, clawed, obovate
petals. The fruits are 1-11/2-cm. (1/2-to 3/4-inch),
stout, club-like beaked capsules that are tightly
appressed against the inflorescence axis. This
mustard is native to the Mediterranean.
Hirschfeldt, 1742-1792, was a horticulturist.
Incana means "gray."
("mustard" in Spanish) was introduced by Spaniards.
Young greens and seeds are eaten.
(Hordeum murinum, Poaceae)
ryegrass (Lolium multiflorum, Poaceae)
(Marrubium vulgare, Lamiaceae) This is
a 1- to 6-dm. (1/2-to 2-foot) perennial that
grows in mounds. Its squarish woolly stems bear
gray-green, opposite, rounded, hairy leaves.The
leaves have conspicuous veins and puckering.
The inflorescence consists of dense clusters
(whorls) of small white flowers. The tubular
calyx has ten hooked teeth. Horehound blooms
in spring and summer. Fruits are nutlets within
a bur. Horehound is native to Europe.
is Hebrew for "bitter juice." Vulgare
burclover (Medicago polymorpha, Fabaceae)
This is a 1- to 4-dm. (4- to 16-inch) prostrate
to ascending annual. It has glabrous stems.
The pinnately compound leaves have three wedge-shaped
leaflets. The inflorescence is a raceme of two
to six yellow flowers. The fruit is a coiled,
prickly bur (legume). This plant is native to
Eurasia, the Mediterranean, and North Africa.
is the Greek name for the related species alfalfa,
Medicago sativa, which arrived to Greece
via Medea. Polymorpha means "many forms."
annual yellow sweet-clover (Melilotus
indica, Fabaceae) This is a sweet-smelling
annual. It has glabrous, spreading to erect
1- to 6-dm. (4- to 24-inch) stems. It has pinnately
trifoliolate leaves with 1- to 21/2-cm. (1/2-
to 1-inch), oblanceolate to wedge-shaped, sharply
toothed leaflets. Its inflorescence is a slender
and compact raceme about 1- to 2-cm (1/2- to
1-inch) long. Yellow flowers have 21/2-cm. (1-inch)
petals. Fruits are much smaller indehiscent
one-seeded legumes. Sourclover is found in open,
disturbed areas. It is native to the Mediterranean.
is Greek for "honey-Lotus." Indica means
tobacco (Nicotiana glauca, Solanaceae)
Tree tobacco is a 2- to 6-m. (6- to 20-foot)
shrub or small tree. It has ovate, smooth, glaucous,
bluish-green leaves. Its 30- to 35-mm. (11/2-
to 2-inch) yellow, tubular flowers bloom at
branch tips year-round. The fruit is a capsule
with many tiny black seeds. Tree tobacco is
native to South America. All parts of the plant
are TOXIC if ingested.
Nicot, 1530-1600, is said to have introduced
tobacco to Europe. Glauca means "bluish-gray,"
referring to the powdery coating on this plant.
buttercup (Oxalis pes-caprae, Oxalidaceae)
This perennial has stems that are mostly underground
where it produces many small bulbs. The basal
rosette of leaves is open. Leaves are compound
and have three 31/2-cm. (11/2-inch) spotted,
heart-shaped leaflets. The showy flowers have
21/2-cm. (1-inch) long yellow petals. They bloom
from November through June. In California the
plants fail to set seed, but spread by bulblets
in disturbed soil. This is a native of South
is Greek for "sour." Pes-caprae means
"foot of the goat" and refers to the shape of
ox-tongue (Picris echioides, Asteraceae)
This annual or biennial has 3- to 8-dm. (1-
to 11/2-foot) coarse, stout stems. Leaves are
basal and cauline. They are oblong, entire,
and coarsely toothed or shallowly lobed. The
2- to 4-cm. (1- to 11/2-inch) inflorescence
is a dandelion-like head of yellow flowers surrounded
by an outer ring of wide, prickly bracts and
an inner ring of narrower, smooth bracts. The
fruit is a brownish achene with a slender beak
and a white pappus. Bristly ox-tongue is native
is Greek for "bitter." Echioides comes
from echinus and means "hedgehog-/sea
plantain (Plantago lanceolata, Plantaginaceae)
This perennial has a stout caudex and taproot.
The 5- to 25-cm. (2- to 10-inch) leaves are
all basal, mostly lanceolate, with several parallel
veins and minutely toothed margins. The inflorescence
is a cone-shaped, dense 2- to 8-cm. (1- to 3-inch)
spike on a 20- to 80-dm. (8- to 32-inch) peduncle.
The four-petaled flowers are inconspicuous.
The fruit is a capsule. English plantain is
native to Europe.
means "sole of foot/footprint." Lanceolata
refers to the leaf shape.
pink (Silene gallica, Caryophyllaceae)
This is a 10- to 40-cm. (4- to 16-inch) hairy,
sticky annual. The nodes of its stems have a
swollen appearance. It has 1- to 31/2-cm. (1/2-
to 11/2-inch), spade-shaped, opposite leaves.
The showy flowers have five white-pink, ovate,
clawed petals that are slightly turned, like
the arms on a windmill. Blooms occur from February
through May. The fruit is a capsule. Windmill
pink is native to Europe.
is probably named after the mythological Silenus
(who was covered with foam, referring to the
sticky secretions of many species in this genus).
Gallica means "French."
thistle (Silybum marianum, Asteraceae)
This is a 2- to 30-dm. (3/4- to 9-foot) annual.
Its leaves are large, deeply lobed and coarsely
toothed, and have wavy margins. The teeth and
lobes are tipped with rigid spines. The leaves
are shiny green with irregular bold white botches.
Flowers are in 2- to 6-cm. (3/4- to 21/3-inch)
spiny-bracted heads at branch tips. The flowers
are rose-purple tubular florets that bloom from
May through July. The fruit is an achene. This
plant is native to the Mediterranean.
is Greek referring to thistle used for food.
Marianum means "of Mary."
sow-thistle (Sonchus asper, Asteraceae)
This is a 1- to 12-dm. (4-inch to 4-foot) annual
with milky sap. Some leaves are basal. Along
the stem, there are also clasping, lobed leaves
that have toothed blades. The teeth and the
lobes are tipped with soft spines. The clasping
lobes at the base of the leaf are spirally coiled.
The inflorescence is a bristly-glandular dandelion-like
head of yellow, ligulate flowers. The fruit
is a flat, ribbed, beakless achene with a pappus
of bristles. Prickly sow-thistle is native to
Eurasia and Africa.
is the ancient Greek name for this plant. Asperum
means "rough, with minute points."
sow-thistle (Sonchus oleraceus, Asteraceae)
This is a 1- to 14-dm. (4-inch to 41/2-foot)
annual with milky sap. It has basal and cauline
leaves. The cauline leaves are clasping and
have lobed blades whose terminal lobe may be
shaped like an arrowhead. The clasping lobes
at the base of the leaf are straight and sharply
pointed. The inflorescence is a dandelion-like
head of yellow, ligulate flowers. The fruit
is a flat, ribbed, beakless achene with a pappus
of white bristles. Common sow-thistle is native
is the ancient Greek name for this plant. Oleraceus
in Spanish, comes from cardar meaning
to card or comb wool, a use of this plant.
(Stellaria media, Caryophyllaceae)This
is a 7- to 50-cm. (23/4- to 20-inch) annual
with weak, trailing, hairy stems. The leaves
have 8- to 45-mm. (1/3- to 2-inch) ovate blades
and are arranged opposite one another on the
stem. The white flowers have 31/2-mm. (1/8-inch)
petals that are two-parted at the tips. Chickweed
may bloom all year in sheltered places, but
mostly from February through April. The fruit
is an ovate capsule. Chickweed is native to
comes from the Latin stella, meaning
star and referring to the shape of the flower.
Media means "intermediate" or "middle-sized."