Contribution to the fine anatomy and histochemistry of birdseye sugar maple

Abstract

Light and transmission electron microscope observations of birdseye tissues in sugar maple revealed the following features in the xylem: inclined axial elements, vessels smaller and shorter than the ones found in adjacent normal xylem, occasional gaps between xylem cells, abnormal thickenings of vessel secondary walls, and absence of multiseriate rays. Histochemical and cytochemical tests also indicated that birdseye xylem was less lignified than adjacent normal xylem. When this figure appeared in more than five consecutive growth rings, collapsed and hypertrophied cells were observed at the beginning of rings. These abnormal cells seemed to show that cambial initials were injured at the start of the growing season. The injury apparently occurred following a pressure exerted on a group of fibres present in the inner bark, very close to the cambium. After forming these unusual cells, the cambium resumed production of more typical elements. In birdseye tissues, the phloem layer was reduced and rays showed many anomalies. These anatomical changes may have induced poor translocation of nutrients to the cambium, eventually leading to abnormal differentiation of xylem derivatives. High levels of ethylene may have stimulated phellogen activities that could have generated a pressure toward the cambium. Future studies on birdseye formation are also suggested. Résumé :Les observations en microscopie photonique et microscopie électronique à transmission ont révélé les caractéristiques suivantes chez le bois piqué de l'érable : des éléments longitudinaux inclinés, des vaisseaux plus courts et de diamètres inférieurs à ceux présents dans le xylème normal, occasionnellement des trous entre les cellules, des épaississements inhabituels de la paroi secondaire des vaisseaux et une absence de rayons multisériés. Les tests histochimiques et cytochimiques ont révélé que le bois piqué était moins lignifié que le bois normal. Lorsque les mouchetures étaient observées sur plus de cinq cernes de croissance consécutifs, des cellules affaissées et hypertrophiées étaient observées au début des cernes. Ces cellules anormales suggèrent que les initiales du cambium ont été endommagées. Ce dommage a apparemment été causé par une pression exercée sur un groupe de fibres localisées tout près du cambium. Le cambium a recommencé par la suite à former des éléments du xylème plus normaux. Cette pression venant de l'écorce pourrait avoir contribué à produire un phloème plus mince et des rayons montrant des anomalies, le tout ayant probablement affecté directement la translocation d'éléments nutritifs vers le cambium et, concurremment, la différenciation des éléments du xylème. De fortes concentrations d'éthylène pourraient avoir stimulé le fonctionnement du phellogène et avoir ainsi généré une pression vers le cambium. Des études additionnelles sur la formation de ces mouchetures sont aussi suggérées. Rioux et al. 958

The onset of hazel wood formation in Norway spruce (Picea abies [L.] Karst.) stems

“…The abnormal development of the secondary phloem generates pressure on sensitive cambial cells, which potentially disturbs their metabolism and reduces the growth of xylem cell elements. The depth of the generated depression however was small during the onset of the indentation and changed only slightly over the next few years (Rioux et al 2003). Contrary to the formation of birdseyes, we found that frequent malformations of both tracheids and parenchyma cells, accompanied with cell hypertrophy, immediately produced the formation of substantial lenticular depressions.…”

“…The indentation of annual growth rings is usually caused by a local suppression of growth, where single cell elements are strongly bent, thereby resulting in the formation of depressions (Beals and Davis 1977;Rioux et al 2003). A reduction in the formation of cell elements in the xylem may also occur during the onset of a birdseye structure formation in Acer saccharum (Rioux et al 2003).…”

“…A reduction in the formation of cell elements in the xylem may also occur during the onset of a birdseye structure formation in Acer saccharum (Rioux et al 2003). Birdseye is referred to as an aberration in the normal grain pattern of maples where an indentation in the wood forms at localized points along the stem, branches, bark, and perhaps also on the roots (Bragg 2006).…”

Diagnostic features of Fraxinus excelsior L. with wavy-grained wood growing in Ukraine

“…but do not include the decorative wood characteristics: width and height of anomaly wood formation, its number etc. Thereby, the decorative value of ash wood is important in the context of its classification by quantifiable or explicable charac-teristics (Yatsenko-Khmelevskyy 1954; Rioux et al 2003;Vintoniv et al 2007;Sopushynskyy 2006Sopushynskyy , 2012.…”

Figured grain in aspen is heritable and not affected by graft-transmissible signals

“…The occurrence of figure is rare, which makes wood possessing it more valuable than non-figured wood of the same species (Beals and Davis 1977;Harris 1989;Bragg 1999;Rioux et al 2003). Despite the commercial value of figured wood, study of the mechanism responsible for its formation has been limited.…”