Thistle Identification Referee 2017 Southwest Region Deborah Meyer
Thistle Identification Referee 2017 Southwest Region Deborah Meyer & Robert Price California Department of Food & Agriculture
Purpose • Review morphological characters that are useful for identification of thistle and knapweed fruits. • Review useful resources for making identifications. • Review resources used to make decisions on classification into common and noxious weed seeds. • Identify seeds from less than ideal photographs.
Referee Structure Participants were to answer 28 questions related to identification of thistle and knapweed fruits: Ø 24 multiple choice Ø 4 short answer Participants were provided an identification guide consisting of color photographs and descriptions of 42 species of common and noxious thistle and knapweed fruits (Meyer 2017). Some questions required participants to use other reference resources of their choosing. Identification guide and questions distributed by the AOSA/SCST Executive Office to all members via email, and posted on the AOSA/SCST Referee Committee website.
Overall Scores (% Correct) Responses received from 87 participants. (38 government, 49 non-government)
Percentages of Correct Responses Blue = Morphology Green = Resource Management Dark orange = Identification Light orange = Identification + Resource Management
Structures in General 10. The outer layer of this structure is a. Seed coat b. Testa c. Pericarp d. Perianth 74% responses correct 11. What is the name of this structure? a. Hilum b. Point of fruit attachment c. Stigma d. Style base 100% responses correct 97% responses correct 12. What is the name of this area of the fruit in Centaurea? a. Pappus ring b. Scar rim c. Elaiosome ring d. Apical rim 13. This structure is: a. Attractive to ants b. Helpful to fruit dispersal c. Persistent on all fruits of Centaurea solstitialis d. Attached to the base of the inferior ovary 91% responses correct 90% responses correct 14. What is the name of this structure? a. Hilum b. Point of fruit attachment c. Stigma d. Style base
Structures in General 1. In the Asteraceae, the pappus represents this floral structure: a. Modified stigma b. Modified corolla c. Modified calyx d. Modified perianth 98% responses correct 16. What is the structure indicated by the arrow? a. Apical rim b. Elaiosome c. Hilum d. Style base 94% responses correct 15. The margin of this apical rim can be described as: a. Crenulate b. Dentate c. Lanceolate d. Oblanceolate 99% responses correct
Association of Structures with Taxon 3. Which of the following genera has a pappus comprised of plumose bristles? a. Centaurea b. Carduus c. Silybum d. Cirsium 86% responses correct 4. Which of the following species has the largest fruit? a. Cirsium arvense b. Cirsium japonicum c. Cirsium undulatum d. Cirsium vulgare 100% responses correct 17. What species has an inner pappus whorl consisting of a single broad scale? a. Carthamus lanatus b. Centaurea benedicta c. Mantisalca salmantica d. Volutaria muricata 97% responses correct 2. Which of the following species has an epappose fruit? a. Centaurea calcitrapa b. Cirsium vulgare c. Onopordum acaulon d. Cynara cardunculus 97% responses correct 5. Which of the following species has a pappus that hides the style base? a. Volutaria muricata b. Mantisalca salmantica c. Centaurea solstitialis d. Crupina vulgaris 95% responses correct
Additional Resources Required 6. Which of the following species is classified as a noxious weed somewhere in the United States? a. Amberboa moschata b. Centaurea cineraria c. Centaurea cyanus d. Mantisalca salmantica 97% responses correct 100% of participants used the All States Noxious List to answer question. 8. To what region of the world is Mantisalca salmantica native? a. South Western United States b. Mediterranean Region c. Southern Africa d. Pacific Northwestern United States 74% responses correct Resources used by participants varied. 28. According to Vol. 3 of the AOSA Rules, which name listed below is the currently accepted scientific name for Russian knapweed? a. Acroptilon repens b. Centaurea repens c. Centaurea picris d. Rhaponticum repens 98% responses correct
Identification of Photos These 3 questions related to this photo. 25. Name one other genus in the Asteraceae shown in this photo that is considered a noxious weed seed in California. Answer: Onopordum 84% responses correct 23. Name the species of the object circled and labeled as 23 in this photo? a. Centaurea diffusa b. Centaurea jacea c. Centaurea melitensis d. Centaurea solstitialis 32% responses correct 24. In what state is the object circled and labeled as 24 classified as a noxious weed seed? a. Nebraska b. Nevada c. New Jersey d. New Mexico e. North Carolina f. North Dakota 89% responses correct
Identification of Photos 18. What species is this? a. Carthamus oxycantha b. Carthamus tinctorius c. Centaurea jacea d. Rhaponticum repens 95% responses correct 21. What species is the contaminant in this white clover sample? a. Centaurea diffusa b. Centaurea solstitialis c. Centaurea stoebe d. Centaurea virgata 100% responses correct 19. What species is this? a. Carthamus oxycantha b. Carthamus tinctorius c. Centaurea jacea d. Rhaponticum repens 91% responses correct 20. The species in question #19 is: a. Pappose b. Epappose 79% responses correct
Identification of Photos Carduus acanthoides Carduus pycnocephalus Carduus nutans Cirsium arvense Cirsium undulatum 26. What species is represented by the specimen labeled A? a. Carduus acanthoides b. Carduus nutans c. Carduus pycnocephalus d. Cirsium arvense e. Cirsium undulatum 79% responses correct 27. What species is represented by the specimen labeled B? a. Carduus acanthoides b. Carduus nutans c. Carduus pycnocephalus d. Cirsium arvense e. Cirsium undulatum 26% responses correct
- Slides: 12