From the dark leaves of coastal scrub oak and black sage, to the bright hues of coyote brush and coastal prickly pear cactus, St. Patrick’s Day green is a common color around the Irvine Ranch Natural Landmarks this time of year. Recent rains and the winter season – when native plants come out of dormancy – have made the green shades even more prominent.
​
There are a variety of activities out on the Landmarks the week of St. Patrick’s Day to spot green in full force, whether during a fast-paced hike, an interactive outdoor adventure or volunteer opportunities giving back.

The first official day of spring isn’t until March 20, but many flowers on the Irvine Ranch Natural Landmarks are already beginning to bloom. Chocolate lilies have been spotted on the slopes of West Loma Ridge in Limestone Canyon Nature Preserve, Weir Canyon Nature Preserve is rich with fields of bright yellow fiddlenecks, and wild hyacinth and sticky monkey flower are plentiful along many trails in Bommer Canyon.

But wildflowers need more than just warm weather and rainfall to thrive long-term. Invasive and non-native plants can steal light and nutrients from native flora, making it harder for native species to grow. In 2012, the small-flowered morning glory – a rare, native flower that was in decline within the Landmarks – was discovered sprouting from dormant seeds in the West Loma Ridge watershed habitat restoration area. This uncommon flower was able to make a comeback in part due to the removal of invasive species; in the absence of weeds, its seeds remaining in the soil were able to return to an environment free of competition from invasive plants.

Wildflowers are starting to appear in local canyons, but not all of these flowers are happy harbingers of spring. Some blooms are signs of invasive weeds threatening native plants and wildlife of the Irvine Ranch Natural Landmarks. And while spring is the season to spot native wildflowers, it’s also a critical time to remove one of the most dangerous and invasive threats to our protected wild lands: Sahara mustard. You can help by volunteering to remove this invasive weed and help restore wildlife habitat.

Sahara mustard (Brassica tournefortii) is a highly aggressive invasive weed that is more of an immediate threat to native flora and fauna than other, more-prevalent mustard such as black mustard (Brassica nigra). Despite Sahara mustard’s tiny, pale yellow flowers that look pretty for a short while, its ability to quickly and easily invade and replace healthy habitat makes it a prominent threat to the Landmarks. The weed can quickly spread its seed, grow rapidly, making it a top priority for removal before it establishes too much of a hold within the Landmarks. When invasive weeds drive out native plants, they also drive out the wildlife that depends on native plants for food and shelter. Public support is vital to stopping the weed’s spread and ensuring the continued protection of one of Orange County’s most diverse open spaces.

Volunteers help native plants and wildlife return to Quail Hill Loop.

Though artichoke thistle may look attractive with its bright purple flower, there is no questioning this weed’s destructive nature to the Irvine Ranch Natural Landmarks. Its aggressive root system and rapid leaf growth steals light, water and nutrients from native plants. Each plant can also produce tens of thousands of seeds per year that are blown by wind or hitchhike on animals. If left unchecked, artichoke thistle can quickly spread across a landscape, displacing native plant diversity in its path. The artichoke thistle is one of the worst threats to natural habitat within the City of Irvine Open Space Preserve’s Quail Hill.

The few can be mighty, and nothing better attests to that than the work and rewards of community stewardship.

Irvine Ranch Natural Landmarks are rich in oak-filled valleys, expansive grasslands and plentiful coastal sage. Protecting those lands from invasive non-native plants to keep wildlife thriving takes attentive, consistent and continuous dedication.

This is where community volunteers have the biggest impact – dedicating muscle and manpower to protecting nearly 40,000 acres of open space. Even the smallest amount of effort goes far in habitat restoration; for instance, a modest team of workers last week pulled 20,000 invasive plants from OC Parks’ Limestone Canyon Nature Preserve in just two days.