Cyathium morphology of Euphorbia spathulata from three populations in central Virginia was studied from early developmental stages through nominal anthesis, defined by exposure of the cyathium to the external environment by divergence of paired subtending cyathophylls. Observations were made via dissecting microscope, compound light microscope sections, and scanning electron microscopy. The plants studied revealed a consistent pattern of asynchronous stamen and pollen development as well as a series of predictable changes in style and stigma orientation. Initially, styles and stigmas of pistillate flowers maintain a near-axial (erect) position. Later, when still enclosed by subtending cyathophylls, styles reflex, placing stigmas near early developing anthers shedding pollen. Pollen grains observed on stigmas at this stage indicate cleistogamous pollination. Eventually, paired cyathophylls diverge, exposing the cyathium to the external environment; at this stage, styles and stigmas assume an ascendant position as late-maturing anthers shed pollen, a configuration conducive to chasmogamous pollination. These observations indicate that a succession of cleistogamy and chasmogamy characterize the reproductive process of each cyathium of E. spathulata, at least in the populations studied.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 83 • No. 1