purple owls clover

Removing invasive plants and weeds is a large part of the restoration work that takes place in our preserves. This can be challenging, since some invasive species look similar to California natives. Help us protect native plants—become a community scientist and record your observations in the free iNaturalist or Calflora apps. This information helps us monitor the open space lands and identify areas of concern.

Please do not pull any plants on Midpen lands — we follow a strategic plan when dealing with invasive species and removing plants can actually spread the growth of unwanted species.

Native plant and their non-native look-alikes. Can you tell the difference?


Sneezeweed (Helenium puberulum)

Sneezeweed Plant

  • Provides pollen source for bees and butterflies
  • Native Americans used the seed for medicinal purposes
  • Most leaves are on the lower part of the plant
  • Round, brown yellow daisy like flowerheads, blooms June - August

Stinknet (Oncosiphon piluliferum)

Stinknet Plant

  • Native to South African, recently spotted in Stevens Creek Shoreline Preserve
  • Grows in dense clusters and displaces native vegetation
  • Not palatable to livestock or native herbivores such as deer, squirrels and rabbits
  • Flowers are bright yellow globes, blooms March - July


Chaparral Clematis (Clematis lasiantha)

Chaparral Clematis Plant

  • Benefits native bees and butterflies
  • Unisexual flowers, about 1-3” in diameter
  • Climbing vine can grow up to 18 ft tall
  • Creamy white flower, blooms March - July

Old Man’s Beard (Clematis vitalba)

Old Man's Beard Plant

  • Native to the UK, favors forests and woodlands
  • Smothers trees causing them to weaken and collapse
  • Reduces biodiversity by out-competing native plants
  • Spreads via seeds and roots, white flowers blooms July - September


Common Yarrow (Achillea millefolium)

Common Yarrow (Achillea millefolium)

  • This perennial herb can be found in most Midpen preserves
  • Found in grasslands, meadows, open forests and disturbed areas
  • Native Americans used the plant for pain relief and fever reduction
  • About 1-3 ft tall, blooms April - August


Perennial Pepperweed (Lepidium latifolium)

Perennial Pepperweed (Lepidium latifolium)

  • Grows aggressively, forming dense colonies that exclude native plants
  • Native to southeastern Europe to southwestern Asia
  • First recorded sighting in CA was in 1936 in Stanislaus County
  • Reproduces by seed and vegetatively, blooms May - July


Blue Wildrye (Elymus glaucus)

Blue Wildrye by Keir Morse

  • Large perennial bunchgrass found in open areas, native prairie, chaparral, woodland and forest
  • Leaf color is green, blooms May - July
  • Provide wildlife habitat for mammals, birds and waterfowl
  • Important pollinator plant for bees and butterflies

Jointed Goatgrass (Aegilops cylindrica)

Jointed Goatgrass

  • Annual grass from west Asia and eastern Europe
  • Found in wheat fields and other cropland areas.
  • About 15 - 30 inches tall, blooms May - July
  • Produces about 3,000 seeds per plant which remain viable for 3-5 years


California Aster (Symphyotrichum chilense)

California Aster

  • Grows in grassland, meadows, salt marshes, costal dunes and costal scrub habitats
  • Deep, fibrous root systems help with erosion control
  • Violet/pink or white flowers with yellow centers bloom July - August
  • Excellent pollinator plant, provides pollen for bees and nectar for checkerspot and crescent butterflies

Ox-Eye Daisy (Leucanthemum vulgare)

Ox-Eye Daisy by Dr Nick V. Kurzenkeo

  • Found in roadsides, pastures, grassland, coastal scrub and open forests
  • Rosette leaves grow up to 6 inches long
  • White daisy flower with yellow centers bloom May - August
  • Invasive perennial herb from Europe that grows densely and excludes other vegetation


Pacific Bleeding Heart (Dicentra formosa)

Pacific Bleeding Heart

  • Perennial herb in the poppy family
  • Delicate, fern-like leaves
  • Rose-purple to cream flowers bloom March - May
  • Provides excellent habitat and food supply for birds and insects

Herb Robert (Geranium purpureum)

Herb Robert

  • Leaves are light green and turn red in late fall
  • Strong smell of diesel and mint when crushed
  • Pink flowers bloom March - May
  • Escaped from ornamental plantings, displaces native plants in forested communities as groundcover


California Blackberry (
Rubus ursinus)

California blackberry

  • Upright, sprawling vine or shrub
  • Typically has three leaflets
  • White, fragrant flowers bloom February - May
  • Valuable for preventing soil erosion at disturbed sites due to its ability to grow in infertile soils


Himalayan Blackberry (Rubus armeniacus)

Himalayan Blackberry

  • Sprawling, evergreen shrub
  • Typically has five leaflets and large thorns 
  • White/light pink flowers bloom April - August
  • Rapidly displaces native plant species by producing dense canopy and limiting sunlight for understory plants


California Bay Laurel (Umbellularia californica)

California Bay Laurel

  • Broad-leaved evergreen tree
  • Height: 25-40 feet, old trees can reach 100 feet
  • Creamy white-yellowish flowers bloom April - September
  • Nicknamed “pepperwood,” because of the pepper scent, dried leaves are used in cooking.


Blue Gum Eucalyptus (Eucalyptus globulus)

Blue Gum Eucalyptus

  • Tree with long, waxy blue leaves
  • Height: 150-180 feet
  • White flowers bloom October - March
  • Fruit, leaf and bark litter is extremely flammable