Field Guide to Plant Galls of California and Other Western States (California Natural History Guides)

Field Guide to Plant Galls of California and Other Western States (California Natural History Guides)

Language: English

Pages: 400

ISBN: 0520248864

Format: PDF / Kindle (mobi) / ePub


Oak apples, honeydew and ambrosia galls, witches’ brooms, and fasciations—all are types of plant galls, a commonly observed, yet little-understood botanical phenomenon. Often beautiful and bizarre, galls are growths of various shapes, sizes, and colors produced by host plants in response to invading organisms. This guide, a trove of natural history lore, explores this hidden realm, taking a fascinating look at the world of plant galls, the organisms that initiate them, their host plants, and their intricate behaviors. Focusing on native trees and shrubs, but also discussing several galls that occur on herbaceous and ornamental plants, it illuminates the complex interrelationship between botany and entomology and magnifies our awareness of plant communities in the West.

* Identifies more than 300 species of galls—95 on oaks, 22 on members of the rose family, 60 desert species, and 35 species that are new to science

* Describes plant galls from coastal dunes, the high Sierra, the Great Basin, forests throughout the western states, and the Mojave and Sonoran deserts

* Includes information on host selection, growth and development, predator and parasite defense, and animal and human uses of galls

 

 

 

 

 

 

 

 

 

 

 

 

B on cypress. Douglas-fir Galls Douglas-fir (Pseudotsuga menziesii) is not a true fir. It is galled by a bacterium, a mistletoe, and at least three gall midges, one of which is described here in detail. References: Furniss and Carolin 1977; Sinclair et al. 1987; Gagné 1989; Scharpf 1993. DOUGLAS-FIR STEM GALL Undescribed Pl. 43 This is a globular, round, abruptly swollen gall that can exceed 30 cm (1 ft) across but are mostly under 10 cm (4 in.). Galls appear on twigs, branches, and trunks of

swelling to occur around the larvae. There may be several larvae per needle, with two or more galls occurring away from the usual location at the base of the needle. Full-grown larvae drop to the ground in late fall and early winter and then pupate in spring. Heavy infestations cause the needles to drop and twigs to die. This is a serious pest of trees grown on farms. The other two gall midges on needles of this host are C. constricta and C. cuniculator. Both occur from British Columbia to

in spring. Little is known about the biology of this wasp. It appears to be a southern species occurring on scrub oaks in the Mojave Desert and other parts of San Bernardino County, as well as on Santa Catalina Island. The gall appeared in Weld’s Cynipid Galls of the Pacific Slope (1957, fig. 101) and was labeled as unidentified. The species was finally studied and described by Burnett in 1974. WHITE OAK GALLS 153 Plate 106. The gall of Andricus wiltzae on valley oak. ROSETTE GALL WASP Andricus

also occur on related species of oaks in other desert areas. These galls usually have a pair of distinctive, prominent, rounded, teatlike projections at the apex. Galls found in November were wrinkled, but it is possible that they lack wrinkles when fresh. These udderlike galls measure 8 to 10 mm high by 7 mm wide. They usually occur one per leaf, but occasionally in separate pairs. This species is common among the oaks in Joshua Trees National Park and was discovered in 2004 during the fieldwork

stem gall of Dryocosmus asymmetricus showing the exposed larval chambers on canyon live oak. might be, however, a disadvantage due to the exposure of the pupae and adults (prior to emergence) to parasites and predators. Adults appear to emerge before fall. As with some others, this species also occurs on a variety of canyon live oak in the Southwest. WOOLLY GALL WASP Heteroecus dasydactyli Figs. 48, 49 This cynipid wasp induces detachable, globular, monothalamous, woolly, unisexual

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