Cyclospermum spp.

marsh parsley

Apiaceae Tropical and subtropical Americas

Native to North America

SunFull Sun – Part Shade

Overview

Cyclospermum spp. is a genus of about three to four annual and short-lived biennial herbs in the carrot family (Apiaceae). Plants form low, branching mounds 4-24 inches (10-60 cm) tall, with hollow, grooved stems and leaves finely divided into thread-like segments 0.2-1.2 inches (5-30 mm) long. The foliage carries a faint celery scent when crushed. Tiny white to greenish flowers, each about 0.04 inch (1 mm) across, are borne in small compound umbels of 2-7 rays, often without the leaf-like bracts seen in related genera. These mature into ribbed, egg-shaped fruits 0.06-0.1 inch (1.5-2.5 mm) long that split into two seeds. The most widespread species, C. leptophyllum, has naturalised across six continents and behaves as a colonising weed of disturbed ground, lawns, and crop margins. Cyclospermum spp. completes its life cycle quickly, often setting seed within a few months of germination, and self-sows freely. Because the genus spans warm-temperate to tropical climates, frost ends the annual forms while milder regions allow autumn-germinated plants to overwinter as small rosettes. The plants have little structural bulk and are most often encountered as a weed rather than a cultivated subject, though the seeds and foliage of some species have a history of culinary and herbal use in parts of South America.

Native Range

Cyclospermum spp. is native to the tropical and subtropical Americas, from the southern United States through Mexico, Central America, the Caribbean, and much of South America. C. leptophyllum has spread far beyond this range and is now naturalised in Africa, southern Europe, Asia, and Australia.

Suggested Uses

Cyclospermum spp. is seldom grown as an ornamental and is most familiar as a volunteer of cultivated and waste ground. The foliage and seeds of C. leptophyllum have been used as a culinary flavouring and in traditional herbal preparations in parts of South America. In a garden setting the genus is generally managed as a weed rather than a planted subject.

How to Identify

Look for low, much-branched annual herbs with hollow grooved stems and leaves finely divided into narrow, thread-like segments that release a celery-like scent when bruised. The tiny white to greenish flowers sit in compact compound umbels of 2-7 rays, usually lacking the conspicuous bracts found in many other Apiaceae. Ribbed oval fruits 0.06-0.1 inch (1.5-2.5 mm) long follow the flowers and split into two one-seeded halves. The overall plant is slight, rarely exceeding 24 inches (60 cm).

Appearance

Size & Dimensions

Height4" - 2'

Width/Spread6" - 1'6"

Colors

Flower Colors

white

green

Foliage Colors

green

Bloom Information

Bloom Period

~12 weeks

Spring Summer

Flowering occurs mainly from late spring through summer, though in frost-free regions Cyclospermum spp. can flower across much of the year wherever moisture is available. Individual umbels are short-lived, but plants produce them in succession over several weeks. Seed set follows quickly, allowing two or more generations in a single warm season.

Detailed Descriptions

Flower Description

white to greenish-white

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

sand loam clay

Drainageaverage

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Cyclospermum spp. grows readily in full sun to part shade on moist, disturbed soils and tolerates a wide range of textures from sand to clay. The annual species need no special care and complete their cycle on natural rainfall in most temperate and subtropical climates. Consistent soil moisture lengthens the growing period, while drought hastens flowering and senescence. The genus is rarely cultivated deliberately; where plants appear in lawns or beds they can be removed by hand or hoeing before seed sets. No serious pests or diseases affect the genus, although seedlings compete poorly against denser vegetation. Most species are short-lived and depend on open ground for recruitment.

Pruning

No pruning is required for these short-lived herbs. Where self-seeding is unwanted, plants can be pulled or cut before the fruits ripen. Removing spent plants at the end of the season clears space for the following year's seedlings.