Abstract Detail

Systematics

Garoutte, Christopher Scott [1], Guilliams, C. Matt [1].

Gathering new evidence for an old problem: the case of the island endemic, Heteromeles arbutifolia var. macrocarpa.

In 1932, Munz described Heteromeles arbutifolia (Lindl.) M.Roem. var. macrocarpa (Munz) Munz (originally as Photinia arbutifolia Lindl. var. macrocarpa Munz) as a new variety of toyon endemic to Santa Catalina (SCa) and San Clemente (SCl) islands. Consistent with the common pattern of gigantism on islands, variety macrocarpa was reported to have larger fruits (8-10 mm long) relative to conspecifics from the mainland and the other California Channel Islands (ca. 6 mm long). Since its description, however, variety macrocarpa has not been widely accepted by taxonomists; most floristic treatments recognize no infraspecific taxa in Heteromeles arbutifolia. Using specimens from the Santa Barbara Botanic Garden herbarium, we conducted a preliminary investigation to determine if Heteromeles arbutifolia from SCa and SCl have significantly larger fruits than other island and mainland conspecifics. The length and width of fruits from specimens collected on SCa and SCl were significantly greater than those from specimens collected on the mainland, and were also greater than fruits from the mainland and all other islands treated as a single group. Fruit size was not significantly different, however, between plants from SCa and SCl and plants from the other Channel Islands. While these differences in fruit size are sufficient to demonstrate the need for further study of this taxonomic problem, these data must be interpreted with caution. Measurements obtained from herbarium specimens may be unreliable, as degree of fruit ripeness is sometimes difficult to assess and the fleshy pomes of Heteromeles undoubtedly shrink while drying. More importantly, despite significant differences, the measurements by group are broadly overlapping and without discontinuities. Therefore, future work will focus on obtaining field measurements of living plants and will span the geographic range of the species. Genetic data would also be helpful in assessing the degree to which the plants of Heteromeles differ among islands and between the islands and the mainland.

1 - Santa Barbara Botanic Garden, Conservation and Research, 1212 Mission Canyon Road, Santa Barbara, CA, 93105, USA

Keywords:
Heteromeles
arbutifolia
macrocarpa
California Channel Islands
taxonomy
Munz
endemic
San Clemente Island
Santa Catalina Island
Santa Barbara Botanic Garden.

Presentation Type: Poster
Session: P, Systematics Section/ASPT Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY028
Abstract ID:140
Candidate for Awards:None