Spring Flowers &
Foliage Guide

The grandest tree of the Central Valley riparian forest and the dominant canopy species along the Lodi Lake Nature Trail. Valley oaks can live 400–600 years and grow to 100 feet tall with massive, wide-spreading crowns. In spring, the deeply lobed, dark-green leaves emerge as chartreuse and bronze, and slender yellow-green catkins dangle in festive clusters. The bark is thick, deeply furrowed, and gray-brown — a hallmark of old-growth specimens. Acorns mature in a single season and are a critical wildlife food source for deer, woodpeckers, scrub jays, and squirrels.

One of the most spectacular sights of the spring riparian forest — and one of the most audible. The Fremont Cottonwood's triangular, bright-green leaves shimmer and clatter in the slightest breeze, creating a constant rustling soundtrack along the trail. In late spring, female trees release vast quantities of cottony white seeds that fill the air like snow. Catkins appear before the leaves. Growing 40–100 feet tall, cottonwoods colonize streambanks and sandbars and are among the fastest-growing native trees in California. Cavity-nesting birds like Great Horned Owls prize the older, hollow-trunked trees.

The most abundant willow found along the Mokelumne River corridor, Arroyo Willow forms dense thickets at the water's edge and along the Lodi Lake and Pig Lake shorelines. In early spring it is one of the first shrubs to leaf out, its lance-shaped leaves emerging a fresh, bright green. Fuzzy silver-white catkins ("pussy willows") appear in February–March, providing critical early-season pollen for native bees. Arroyo willows rarely exceed 30 feet but form multi-stemmed, graceful arching thickets. Their deep, fibrous root systems stabilize stream banks and filter runoff, making them ecologically essential.

One of the showiest native shrubs of spring, Blue Elderberry erupts in April and May with enormous, flat-topped clusters of tiny creamy-white flowers that perfume the air and draw clouds of pollinators. Growing 6–20 feet tall, the shrub has distinctive compound leaves with 5–9 leaflets and a noticeable musky scent when crushed. By late summer the flower heads transform into heavy drooping clusters of dusty-blue-black berries, beloved by over 50 bird species and important to Indigenous peoples for food, medicine, and the manufacture of flutes and game pieces.

A fragrant, arching shrub adorned in spring and early summer with delicate five-petaled pink flowers and a heady perfume. California Wild Rose grows 3–8 feet tall and forms dense, thorny thickets along the edges of the Nature Trail, providing protective nesting cover for small birds and mammals. The compound leaves have 5–7 toothed leaflets and turn orange in autumn. Bright red rose hips follow the flowers and persist into winter, offering food for birds when other sources are scarce. Historically used by California Indian peoples for food, medicine, and ceremony.

A vigorous, woody deciduous vine that climbs high into the canopy of oaks and cottonwoods, sometimes completely draping entire trees in a verdant curtain of broad, slightly heart-shaped leaves. In spring the new leaves emerge with soft fuzz and a reddish tinge before maturing to bright green. Tiny clusters of fragrant greenish flowers bloom in May–June, followed by small, dark purple grapes by fall. Early California explorers wrote of grapevines so thick along river corridors that they blocked views of the water entirely — Lodi Lake preserves a glimpse of this historical abundance.

A common and ecologically important native that grows as a low shrub or high-climbing vine throughout the Nature Trail. In spring the emerging leaves are among the most beautiful in the forest — bright glossy red-bronze with waxy lobing reminiscent of oak leaves. Each leaf is composed of three leaflets ("leaves of three, let it be"). Clusters of small cream flowers bloom in April–May. All parts contain urushiol, an oil that causes severe allergic dermatitis in most people. Despite its hazard to humans, poison oak provides vital food and cover for dozens of bird and mammal species, which are immune to urushiol.

California's beloved state flower blazes along the sunny edges of the Nature Trail from February through May in saturated shades of orange, gold, and cream. The cup-shaped, four-petaled flowers close on cloudy days and at night, opening wide to track the sun. The delicate, blue-green, lacy foliage is a perfect foil to the fiery blooms. An annual or short-lived perennial, the California Poppy self-seeds prolifically and thrives in disturbed, well-drained soils. At Lodi Lake, look for it along trail margins and open areas near the parking areas.

One of the most charming and common wildflowers of spring in the Central Valley, Miniature Lupine grows 4–16 inches tall and produces densely packed spikes of violet-blue and white pea-shaped flowers from March through May. The palmate leaves, arranged in a pinwheel of 5–7 leaflets, trap dew drops in their centers at dawn. As a legume, lupine fixes atmospheric nitrogen into the soil, improving soil fertility for neighboring plants. Look for it in sunny, grassy openings along the trail edges and in the transition zones between the forest and open areas near the lakes.

A graceful, aromatic perennial herb that forms dense colonies 2–5 feet tall along the shaded edges of the Nature Trail and around Lodi Lake. The deeply lobed leaves have a distinctive two-tone quality — rich green on top and brilliant white-silver beneath — that creates a shimmering, dappled effect when a breeze moves through a stand. Crushing a leaf releases a powerfully sage-like, camphor-rich fragrance. In late summer, small inconspicuous flowers appear. Mugwort spreads aggressively via rhizomes and often forms large patches. It was one of the most important medicinal plants used by California Indian peoples.

The iconic emergent plant of California's Central Valley wetlands, Tule forms towering stands of olive-green, cylindrical stems 5–10 feet tall at the edges of Lodi Lake and Pig Lake. The stems are spongy, round in cross-section, and topped in spring with small brown-reddish flower clusters. Tule marshes are among the most productive wildlife habitats in North America — providing nesting, feeding, and cover for Red-winged Blackbirds, Coots, Bitterns, River Otters, and countless invertebrates. The word "tule" comes from the Nahuatl language; Central Valley fogs are still called "tule fog."

Instantly recognizable by its iconic brown, sausage-shaped seed heads, Common Cattail is abundant in the shallow-water margins of Lodi Lake and Pig Lake. The flat, strap-like leaves grow 4–8 feet tall. In spring, the male and female flower heads develop on the same stem — the yellow, pollen-producing male spike at the top, the familiar dense brown female spike below. By fall the seed heads burst into a cloud of cottony fluff, dispersing seeds on the wind. Cattail is among the most useful plants in the natural world — nearly every part is edible or useful to wildlife and humans alike.

A beautiful floating aquatic perennial found in the calmer, slower sections of Lodi Lake and Pig Lake. Round to heart-shaped, leathery floating leaves 8–16 inches across provide shade, oxygenation, and resting platforms for turtles and frogs. In spring and early summer, solitary globular yellow flowers emerge on stout stalks just above the water surface, each with 9 waxy yellow sepals surrounding a pad of red stamens and a distinctive yellow disc. The flowers have a subtle, pleasant fragrance. Large spongy rhizomes anchor the plant in bottom sediment.

Native to the Amazon Basin of South America, Water Hyacinth is considered one of the world's worst aquatic invasive plants — and it has been confirmed at Lodi Lake, most likely transported from the Sacramento-San Joaquin Delta on boats or kayaks. The floating rosettes of shiny, balloon-like leaves and showy lavender-purple flowers are deceptively beautiful. Beneath this loveliness lies an ecological nightmare: a single plant can reproduce to cover an entire lake surface in months, blocking sunlight, depleting oxygen, killing fish, and crowding out all native aquatic plants. It can double its population in as little as two weeks.

A South American aquatic invasive rapidly expanding throughout the Sacramento-San Joaquin Delta and surrounding water bodies. Uruguay Water Primrose forms extensive floating and emergent mats of bright green oval leaves adorned with cheerful bright-yellow, six-petaled flowers — making it appear almost ornamental. Do not be fooled: these mats grow up to 8 inches thick and can completely blanket a water surface, blocking light, depleting oxygen, and eliminating native aquatic habitat. The California Department of Parks and Recreation actively controls it in the Delta; vigilance is needed to prevent it from establishing at Lodi Lake and Pig Lake.

The most conspicuous and destructive riparian invasive in California, Giant Reed forms impenetrable thickets of hollow bamboo-like canes 12–30 feet tall. Native to the Mediterranean and Asia, it was introduced to California in the 1820s for erosion control and has since spread explosively along waterways. At Lodi Lake it can be found along stream margins and in disturbed areas. Giant Reed uses four times more water than native riparian plants, outcompetes and eliminates willows, cottonwoods, and native understory plants, increases wildfire risk, and provides almost no value to native wildlife. It is rated as the most invasive plant in California by the Cal-IPC.

Introduced from Armenia (not the Himalayas, despite the name), this blackberry is now one of the most widespread invasive plants in California, forming impenetrable, thorny thickets 6–15 feet tall along the edges of the Nature Trail, Lodi Lake, and Pig Lake. In spring, white five-petaled flowers bloom from April through June. The berries, while delicious and beloved by humans and wildlife, come at an ecological cost: the plant outcompetes and excludes native shrubs like California Wild Rose and Blue Elderberry, converting diverse riparian habitat into monoculture thickets. It is easily distinguished from the native California Blackberry (Rubus ursinus) by its much larger leaflets and more robust, aggressive habit.

Also called "Tall Whitetop," this Eurasian member of the mustard family forms dense, waist-high stands of waxy blue-green leaves crowned in summer with dense clusters of tiny white flowers. Native to Eurasia, it has spread aggressively into California wetlands and riparian areas. At the Cosumnes River Preserve nearby and throughout the San Joaquin valley, it has become a serious management challenge — and it has been documented in the Lodi area. Perennial Pepperweed spreads aggressively by underground rhizomes and is extremely difficult to eradicate once established. Its dense canopy crowds out native sedges, rushes, and wildflowers.