The biology of Borago officinalis L. (Borage)

Biology document BIO2023-02: A companion document to Directive 94-08 (Dir94-08), Assessment Criteria for Determining Environmental Safety of Plant with Novel Traits

On this page

• 1. General administrative information
  • 1.1 Background
  • 1.2 Scope
• 2. Identity
  • 2.1 Name
  • 2.2 Family
  • 2.3 Taxonomy and genetics
• 3. Geographical distribution
  • 3.1 Potential range in North America
• 4. Biology
  • 4.1 Reproductive biology
  • 4.2 Cultivation and use as a crop
  • 4.3 Cultivated crop as a volunteer weed
    • 4.3.1 Cultural/mechanical control
    • 4.3.2 Chemical control
    • 4.3.3 Integrated weed management
  • 4.4 Means of dispersal
  • 4.5 Gene flow during commercial seed and biomass production
• 5. Related species of Borago officinalis
• 6. References

1. General administrative information

1.1 Background

The Canadian Food Inspection Agency's Plant Biotechnology Risk Assessment (PBRA) unit is responsible for assessing the potential risk to the environment from the release of plants with novel traits (PNTs) into the Canadian environment.

Risk assessments conducted by the PBRA unit require biological information about the plant species being assessed. Therefore, these assessments can be done in conjunction with species-specific biology documents that provide the necessary biological information. When a PNT is assessed, these biology documents serve as companion documents to Dir94-08: Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits.

1.2 Scope

This document is intended to provide background information on the biology of Borago officinalis, including:

• its identity
• geographical distribution
• reproductive biology
• related species
• the potential for gene introgression from B. officinalis into relatives

Such information will be used to characterize the potential risk from the release of herbicide-tolerant borage into the Canadian environment with regard to:

• weediness/invasiveness
• gene flow
• impact on biodiversity

2. Identity

2.1 Name

Borago officinalis L.^Footnote 1

2.2 Family

Boraginaceae family, commonly known as the borage family^Footnote 1.

2.3 Taxonomy and genetics

B. officinalis has 2n =2x = 16 chromosomes^Footnote 2.

Taxonomic position^{Footnote 3Footnote 4}

There are different common names for B. officinalis in the literature, such as borage, common borage, starflower, bee flower, bee plant or talewort. In this document, B. officinalis is referred to as borage.

3. Geographical distribution

The native range of borage includes Northern Africa, the Asia-Temperate region and Europe^{Footnote 3Footnote 5}. Borage is cultivated in:

• Europe
• Africa
• Australasia
• Northern America
• Southern America^Footnote 3

3.1 Potential range in North America

The potential range of borage includes all Canadian provinces. Borage is naturalized as a result of human activity in British Columbia, Alberta, Saskatchewan, Manitoba and New Brunswick^Footnote 6. Borage is not established permanently in Ontario, Quebec, Nova Scotia, Prince Edward Island or Newfoundland and Labrador^Footnote 6. Borage may recur in the wild on a near-annual basis, usually close to agricultural cultivation or gardens where it was intentionally planted.

4. Biology

4.1 Reproductive biology

Borage has a massive floral display and strongly depends on pollinators, particularly bees, to increase seed set^{Footnote 7Footnote 8}. Borage flowers are protandrous, meaning the male reproductive organs mature before the female^Footnote 9. Details of the reproductive biology of borage are lacking, and some available information is contradictory (see discussion in Montaner et al. (2010)^Footnote 10). Borage has been reported as both a self-incompatible^Footnote 11 and a self-compatible species^Footnote 10. To date, most borage crops and breeding programs have been managed on the assumption that borage is a primarily outcrossing species^Footnote 2.

There is limited information available in the scientific literature on pollen viability or dispersal. One study showed that pollen grains remain viable for only 48 hours after flower opening^Footnote 12.

4.2 Cultivation and use as a crop

Use: Borage is an annual herb cultivated for medicinal and food uses^Footnote 13. Borage is also commercially cultivated for its seed oil. Borage oil is the richest plant source of gamma-linoleic acid (GLA), an essential and unusual fatty acid. The health benefits of borage oil may include relief of atopic eczema, rheumatoid arthritis, and regulating high cholesterol and hypertension^{Footnote 2Footnote 14}. The volume of traded borage seeds each year is variable, with an estimated range between 500 and 2000 tonnes worldwide^{Footnote 13Footnote 15}.

Cultivation: Borage has an indeterminate flowering habit making it possible to harvest twice in a growing season under favorable conditions, however this is uncommon in Canada^{Footnote 4Footnote 16}. The extended flowering period of borage and the lack of uniformity in maturing seeds, which become dehiscent when mature, are some of the plant characteristics limiting its cultivation^{Footnote 2Footnote 17}.

Information about common borage agronomic practices is scarce and best management practices are not well-defined^Footnote 13. Some limited information about borage agronomic practices (for example, seeding, fertilization, harvest, etc.) are discussed in the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) publication 'Specialty Cropportunities - Borage'^Footnote 4.

Weeds: Health Canada's Pest Management Regulatory Agency maintains a database of approved herbicides. Please refer to this database for current information on registered herbicides for weed control in borage. Some herbicides may only be registered for use and sale in some provinces. Some herbicides may also be registered using a minor use registration^Footnote 18.

Weed control in minor crops such as borage is difficult because of the limited or lack of registered in-crop herbicides available^Footnote 19. The development of herbicide tolerance in borage may expend herbicide options in the future^Footnote 20. Some of the few registered herbicides to control weeds in borage include:

• Carfentrazon-ethyl (group 14 herbicide) to control broadleaf weeds in pre-plant burndown^Footnote 18
• Imazamethabenz-methyl at reduced rates (group 2 herbicide) can be used for post-emergence control of wild mustard and stinkweeds^Footnote 18. Note: may cause damage to the crop, such as yellowing and stunting. See note on product label.
• Some dim-class (group 1 herbicides) can be used post-emergence for control of grassy weeds such as wild oats, foxtail, volunteer cereals, quackgrass and millet^{Footnote 18Footnote 19}.

To control annual weeds, borage producers mostly rely on seeding timing, stale seedbeds or mechanical weeding^Footnote 20.

4.3 Cultivated crop as a volunteer weed

High rates of seed shattering remains a challenge in borage production^Footnote 21. The highest shattering rate occurs at the lowest plant densities because the plants are subjected to more movement by wind^Footnote 4. One study reported that borage drops many seeds that can grow the following year^Footnote 22. Another report suggests that borage seeds can volunteer at least 2 years after growing the crop, but volunteers can be easily controlled by mechanical means^Footnote 21.

Seed dormancy

No studies were found that specifically evaluate the length of time borage seed can remain in the seedbank. However, Osborne (1999)^Footnote 22 suggests that borage seeds can germinate the following season, while Rhoades (2020)^Footnote 21 observed that seeds could germinate in the second growing season.

Weediness

B. officinalis can grow outside of cultivation across all provinces in Canada^Footnote 6. However, borageis not reported as a problematic weed in managed ecosystems in Canada or anywhere in the world, nor is it recorded as being invasive of natural ecosystems. In addition, it is not listed as a noxious weed or noxious seed in Canada in the Weed Seeds Order, 2016.

4.3.1 Cultural/mechanical control

To minimize the number of potential borage volunteers, efforts should be made to reduce seed shattering and harvest losses. This can be done by increasing plant densities^Footnote 4, growing shatter resistant varieties, properly setting combines and sealing any leaks. Volunteers, if present, can be controlled by mechanical means^Footnote 21.

4.3.2 Chemical control

Currently, no herbicides are specifically registered for the control of volunteer borage; however, borage volunteers in other crops can be controlled using registered herbicides for weed control in those crops^Footnote 18.

4.3.3 Integrated weed management

Integrated weed management (IWM) employs a combination of cultural, mechanical and chemical weed control approaches to manage weed populations and maximize crop yields. IWM strategies have not yet been developed for the control of borage volunteers, but it is likely that such an approach will be useful. Practices such as early seeding, increased seeding rates and the use of competitive cultivars will be applicable.

4.4 Means of dispersal

The mechanisms for the movement and dispersal of borage seeds are unclear. Borage seed can potentially be dispersed by wind, but no specific information was found about the distance of dispersal. Borage seed might be dispersed by organisms that consume the seeds, but the role of animals in borage dispersal is not well characterized.

4.5 Gene flow during commercial seed and biomass production

Gene flow between borage plants growing in proximity may occur. The Canadian Seed Growers' Association (CSGA) has set standards for producing Foundation, Registered and Certified B. officinalis seed^Footnote 23.

5. Related species of Borago officinalis

As stated in Section 1.3. B. officinalis is a member of the Boraginacae family. Species of the Boraginacae family are found in Canada and some are considered weeds. Weed species in the Boraginacae family include:

• Echium vulgare L.
• Echium plantagineum
• Hackelia virginiana (L.) I.M. Johnston
• Lappula squarrosa (Retz.) Dumort.
• Anchusa officinalis L.
• Cynoglossum officinale L.
• Buglossoides arvensis (L.) I.M. Johnston

The following details the distribution and habitat for each of these species in Canada.

From the genus Echium:

E. vulgare (blueweed) is an introduced species in British Columbia, Alberta, Manitoba, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia and Newfoundland and Labrador^Footnote 6. It is also present as an ephemeral species in Prince Edward Island^Footnote 6. It is a biennial, occasionally annual or short-lived perennial, weed that is abundant in the inland-east but is rare elsewhere^Footnote 24. It occurs in rocky permanent pastures, abandoned fields, meadows and roadsides^Footnote 24. It is considered a noxious weed in Nova Scotia, Quebec, Manitoba, Alberta and parts of British Columbia^{Footnote 25Footnote 26}.

E. plantagineum (Paterson's curse) has been introduced in Canada but has never persisted in the Canadian environment^{Footnote 6Footnote 27}. It is an annual or biennial that has become invasive in other parts of the world^Footnote 27. It is a prohibited noxious weed, Class 1 in the Canadian Weed Seeds Order, 2016 under the Seeds Act. Paterson's curse is listed on the List of Pests Regulated by Canada and regulated as a pest in Canada under the Plant Protection Act^Footnote 27.

From the genus Hackelia:

H. virginiana (stickseed, beggar's lice) is present as a native species in Ontario and Quebec^Footnote 6. It is a biennial weed that occurs in open woods, thickets and waste land^Footnote 24.

From the genus Lappula:

L. squarrosa (bluebur) is located as an introduced species everywhere in Canada, except in Nunavut^Footnote 6. It is an annual or winter annual weed that occurs in grain fields, pastures, railway grades and waste lands^Footnote 24.

From the genus Anchusa:

A. officinalis (common bugloss) is an introduced species in British Columbia and Ontario but is only considered a regional noxious weed only in British Columbia. This weed is sometimes confused with Echium vulgare^Footnote 28.

From the genus Cynoglossum:

C. officinale (hound's-tongue) is an introduced species in all provinces in Canada except Prince Edward Island and Newfoundland and Labrador. It is a biennial or short-lived perennial weed that occurs in rangeland, pastures, forested areas, roadsides and ditches^{Footnote 28Footnote 29}. It is considered a provincial noxious weed in British Columbia and Alberta^{Footnote 28Footnote 29}.

From the genus Buglossoides:

B. arvensis Johnston (pigeon weed, corn gromwell) is an introduced species in British Columbia, Manitoba, Ontario, Quebec and Nova Scotia^{Footnote 6Footnote 30}. It is an annual weed, common in arable fields^{Footnote 30Footnote 31}.

From the genus Borago:

B. officinalis is the only known Borago species in Canada^Footnote 6.

There is no information concerning the ability of B. officinalis to hybridize with any of the above-mentioned species located in Canada.

No reports of naturally occurring gene flow between B. officinalis and other crops, weeds, or wild species were found in the literature. The potential for the introgression of genetic information from B. officinalis into wild relatives is undetermined.

6. References