Drummond’s Sundrops, Square-Bud Primrose, Compact Gold Calylophus

Calylophus drummondianus

Family: Onagraceae (on-uh-GRAY-see-ee) (Info)
Genus: Calylophus (kal-ee-LOW-fus) (Info)
Species: drummondianus (drum-mond-ee-AH-nus) (Info)



Foliage Color:

Unknown - Tell us

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Water Requirements:

Drought-tolerant; suitable for xeriscaping

Where to Grow:

Unknown - Tell us


12-18 in. (30-45 cm)


12-15 in. (30-38 cm)

15-18 in. (38-45 cm)


USDA Zone 6a: to -23.3 °C (-10 °F)

USDA Zone 6b: to -20.5 °C (-5 °F)

USDA Zone 7a: to -17.7 °C (0 °F)

USDA Zone 7b: to -14.9 °C (5 °F)

USDA Zone 8a: to -12.2 °C (10 °F)

USDA Zone 8b: to -9.4 °C (15 °F)

USDA Zone 9a: to -6.6 °C (20 °F)

USDA Zone 9b: to -3.8 °C (25 °F)

USDA Zone 10a: to -1.1 °C (30 °F)

USDA Zone 10b: to 1.7 °C (35 °F)

Sun Exposure:

Full Sun


Unknown - Tell us

Bloom Color:

Bright Yellow

Bloom Time:

Late Winter/Early Spring

Mid Spring

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall

Mid Fall



Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

Patent Information:

Unknown - Tell us

Propagation Methods:

From seed; direct sow outdoors in fall

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds


This plant has been said to grow in the following regions:

Chandler, Arizona

Green Valley, Arizona

Benicia, California

Chico, California

Red Bluff, California

San Francisco, California

San Leandro, California

Boise, Idaho

Austin, Texas

Crawford, Texas

Fort Worth, Texas

Georgetown, Texas

Helotes, Texas

Rowlett, Texas

San Antonio, Texas (2 reports)

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Gardeners' Notes:


On Apr 3, 2017, chupacerveza from Austin, TX wrote:

Seems indistinguishable from the stemless primrose...?



On Mar 1, 2007, frostweed from Josephine, Arlington, TX (Zone 8a) wrote:

Drummond’s Sundrops, Square-Bud Primrose, Compact Gold Calylophus Calylophus drummondianus is native to Texas ans other States.


On Jan 14, 2006, LindaTX8 from NE Medina Co., TX (Zone 8a) wrote:

The Squarebud Primrose is a native wildflower in Texas. It grows here in my area along the roadsides, very pretty when blooming. I have the kind of this plant that have yellow flowers and black throat and stigma. They're gorgeous in spring, summer and fall. I let them self-sow to make new plants or collect seeds to move them to new areas. One of my absolute most favorite flowers! Although the info given above suggests acidic soil, it does well in alkaline soil, probably preferring it.


On May 22, 2004, kbrehm from Red Bluff, CA wrote:

Red Bluff, CA

I am growing this plant in a raised bed, in full sun, which receives water everyday. I planted two plants late last fall and both plants have exceeded my expectations in both size and showiness. They have spread two feet each and are covered with blooms. They remained evergreen over the winter.


On Sep 20, 2003, htop from San Antonio, TX (Zone 8b) wrote:

San Antonio, TX
A native New Mexico and Texas plant, Drummond’s sundrops is a spreading ground cover closely related to the evening primrose. From March until November, it is covered in clusters with 2 inch wide bright yellow flowers which, when mature, turn to orange. Preferring full sun (it will take light shade with loss of some flowering), it attains a mound that is 1 to 1.5 feet tall and 1.5 feet wide. Not picky about soil types and highly drought tolerant, it is ideal for rock gardens and along walls. No plant is showier per square foot of bloom. After its first flowering, a light trimming will assist in maintaining a neat, compact habit and encourage further flower production. It is a relatively carefree plant which provides months of beauty.