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Title: Directional floral orientation in Joshua trees (Yucca brevifolia)

Author: Warren, Steve; Baggett, L. Scott; Warren, Heather;

Date: 2016

Source: Western North American Naturalist. 76(3): 374-378.

Publication Series: Scientific Journal (JRNL)

Description:

Joshua tree (Yucca brevifolia Engelm.) is a large, arborescent member of the yucca genus. It is an endemic and visually dominant plant in portions of the Mojave Desert, USA. We document the unique and heretofore unreported directional orientation of its flower panicles. The flower panicles grow primarily at the tips of branches that are oriented to the south. When branches with flower panicles are not oriented in a southerly direction, the flower panicles themselves tend to bend or tilt toward the south. This strategy maximizes exposure of the panicles to direct solar radiation, which, within the latitudes where the Joshua tree grows, is always from the south. Such a strategy may minimize the energetic cost of translocating photosynthates from the plant’s leaf rosettes to the flowers. The flower panicles create large, light-colored landing pads for the obligate nocturnal moth pollinator. Residual warmth in the flower panicles may provide a thermal reward for the moth pollinator that emerges shortly after sunset.

Keywords: Joshua tree, Yucca brevifolia, flower panicles, directional orientation, pollination

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

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Citation:


Warren, Steven D.; Baggett, L. Scott; Warren, Heather. 2016. Directional floral orientation in Joshua trees (Yucca brevifolia). Western North American Naturalist. 76(3): 374-378.

 


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