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This page was updated on Monday March 17 2008

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Pampasgrass and Jubatagrass Threaten California Coastal Habitats

How do you tell the difference between the two species?

Pampasgrass and jubatagrass are very similar in appearance and are difficult to distinguish. Even botanists have not made clear distinctions between these two plants until recently. Despite the widespread distribution of jubatagrass, floras prior to The Jepson Manual: Higher Plants of California (1993) recognized only pampasgrass (Cortaderia selloana) in California. While distinguishing between the two species is not important to the use of a specific control technique, the differences in their reproductive biology is critical to the mechanism and potential for spread in each of these species, particularly from sources originating within the nursery industry.

comparison of jubatagrass and pampasgrass plumes

1 - plumes of jubatagrass showing purple coloration;
2 & 3 - male pampasgrass;
4 & 5 - female pampasgrass;
note purplish tinge in male pampasgrass plumes

The major differences between jubatagrass and pampasgrass are listed in the Table. Vegetatively, mature jubatagrass tussocks are generally shorter and broader than the erect, fountain-like tussocks of pampasgrass. The plumes of jubatagrass are purple to tawny in color and are exserted to a greater height above the tussock than the creamy white plumes of female pampasgrass. However, male pampasgrass plants can have plumes that can be as long as jubatagrass, and more violet than female pampasgrass. Thus, they appear to be a cross between jubatagrass and female pampasgrass. These characteristics of the male plants have led some to incorrectly conclude that the two species hybridize.

Character	Jubatagrass (Cortaderia jubata)	Pampasgrass (Cortaderia selloana)
Reproductive traits Reproduction Sex expression Chromosome number	Seed produced asexually Female flowers only 2n=108	Seed produced sexually Male and female flowers on separate plants (female plants can produce a few bisexual flowers) 2n=72
Tussock Typical height at maturity (not including flowering stems)	1-1.5 m (3-5 ft)	2-4 m (6-13 ft)
Leaves Habit Color Tips	Ascend more horizontally, spreading Bright green Appear broader, less coiled	More erect, fountain-like Bluish-green Appear narrower, more coiled
Flowering stems/culms Height above tussock	1-2 m (3-6 ft)	female: 0-1 m (0-3 ft) male: 0-2 m (0-6 ft)
Inflorescence Immature panicle color Mature panicle color 2^o branches rachilla color	Deep violet Pinkish to dingy tan Purplish or dark Purplish or dark	female: white male: white to violet white, cream, male sometimes pinkish-tan green or straw-colored green or straw-colored, male sometimes purplish or dark near spikelet base
Spikelets/Florets/Seed Presence of anthers, stigmas (early flowering stage) Glumes Floret #/spikelet Lemma hairs Lemma length including awn Awns Florets showing stigmas or emerging anthers	stigmas often with purple midvein 3-5 6-10 mm long 10-13 mm 0-4 mm longer than lemma hairs	female: stigmas male: anthers white, male sometimes purplish near base female: 5-7 male: 3-5 female: 1-10mm long male: absent female: 15-20mm male: 10-13mm female: 5-12mm longer than lemma hairs

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