Quercus species

Masuda, M., Nishimura, K. (1971). Branched nonalactones from some Quercus species. Phytochemistry, 10, 1401-1402. 

Definition Extract of the bark of oak trees, Quercus species... 

Aliphatic lactones are important as aroma components in foods and flavors. Among them, y-lactones preferentially occur in plants and J-lactones are mainly found in animal products. The details on naturally-occurring lactones as aroma components are described in the literature (87). It is interesting that quercus lac-tone-a (1) and -b (2), two diastereomeric branched nonlactones, have been detected as ingredients in aged whiskeys (88, 134). These lactones were isolated from woods of some Quercus species which are widely used to make barrels for aging spirits such as whisky and brandy (72, 73). 

Yellow lake might reasonably be defined as any pigment formed by the deposition of a dyestuff onto a base which gives a yellow compound. Historically a wide range of dyestuffs has been used to produce yellow-coloured lakes, notably those from flavonoid sources such as the bark of Quercus species - oak - and the berries of various Rhamnus species - buckthorn (qqv.) bases such as cuttlefish, aluminium hydroxide, marl, chalk and occasionally lead white and starch were used. 

Regulatory Status. GRAS ( 182.20) source not limited to Quercus species. 

Walnut galls Galls from Cynips species, Quercus infectoria Oliv. Tannins... 

Zinc concentrations in forest plants vary considerably. In oaks (Quercus spp.), for example, some species are accumulators, whereas others may be termed discriminators. For individual species, zinc concentrations tend to follow the pattern of roots > foliage > branch > trunk (Van Hook et al. 1980). Small lateral roots accumulate Zn to much greater levels than other vegetation components and are probably most sensitive to changes in zinc inputs. Half-time persistence of zinc in forest ecosystems varies from about 3 years in organic matter components to >200 years for large soil pools (Van Hook et al. 1980). 

The distribution and mass budget of chemical species in the Oak Forest ecosystem have been studied in Hungary. The principal timber species is Quercurs petraea, accounting for 78% of the wood mass Quercus cents accounts for 22%. The shrubs are chiefly represented by Acer campestre and Cornus max, and the grass by the genera Carex, Dactylis, and Poa. 

In some cases, browsing does not appear to lead to induced defenses. Two species of northern European birch (B. pendula and B. pubescens) do not seem to respond to moose browsing with increased chemical defenses (Danell et ah, 1985). After experimental defoliation, the Emory oak of southwestern North America, Quercus emoryi, produces in its regrown leaves 2.5 times as much hydrolyzable tannins than in mature leaves, but lower amounts of condensed tannins. Refoliated branches suffered more, not less herbivory. New leaves have more protein, more water, and are tender. These properties may override any effects of induced chemical defenses, at least for the current growing season (Eaeth, 1992), but the induced compounds may still protect a plant later on, especially in winter. 

Abbreviations of plant species Qr, Quercus rubra Gj, Gardenia jasmlnoldes Ca, Cicer arletlnum Tm, Triglochin marltima ... 

Patterns of polyphenol accumulation In leaves vary among the few temperate forest species which have been studied. Feeny s (42) classic study on oak leaves (Quercus robur) shows leaf tannin levels rising slowly until August, and then Increasing sharply. In the cases of sugar maple (Acer saccharum) and yellow birch (Betula lutea) (44), respectively. 

In Quercus alba the rays represent 28% of the wood volume and in other oak species 19-32% in most other hardwoods the rays occupy about 15% but only 8% of the wood volume in the conifer Sequoia sempervirens (13). The large rays of the oak are so spaced and numerous that a molecule of water diffusing through the side of a barrel must cross five or more large rays if it exits on a straight path or follow a much extended path if it is to go around the rays interposed. These large rays no doubt contribute to the strength and bendability of oak as well as to its dimensional stability and relative impermeability. 

CHOH.(CHOH)2.CH2, (CHOH)2 mw 164.16 monoclinic crysts with a sweet taste mp 234— 35° sol in w si sol in hot, almost insol in cold ale practically insol in eth. Found in the acoms of various species of Quercus Fagaceae (Refs 2, 3 6). Its structure was detd by Kiliani (Ref 7), Postemak (Ref 8), and others (Ref 1, p [1151]). On nitration, it forms an expl compd Quercitol Pentenitrate (Nitroquercite). C6H7(0N02)s, mw 389.16, N 18.00%, OB to CO —2.1% nearly colorl, transparent, resinous substance mp, explds... 

Tannins are abundant in many different plant species, in particular oak (Quercus spp.), chestnut (Castanea spp.), staghorn sumac (Rhus typhina), and fringe cups (Tellima grandiflora). Tannins can be present in the leaves, bark, and fruits, and are thought to protect the plant against infection and herbivory. 

To unravel the effect of local climate conditions on the selective pressure driving the stomatal adjustment, we first focus on leaf morphological and stomatal frequency data of two species with contrasting leaf morphology and geographical distribution over altitudinal transects California black oak (Quercus kelloggii Newberry), the species on which this method was originally based (McElwain 2004), and the mountain beech (N. solandri var. cliffortioides (Hook, f.) Poole) from New Zealand. 

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