Biological and taxonomical investigations of some oak species
Hermaphroditic flowers blooming unseasonably on an oak tree (»the green oak«) of uncertain hybrid origin prompted a detailed investigation into the biology of the flowering, and the morphology of various traits of the tree, which is growing in an urban area near Zadar, northern Dalmatia, Croatia. Hermaphroditic flowers were also detected on one holm oak tree from Weihenstephan, Germany. Since the first oak tree was described as a hybrid between Q. cerris f. austriaca Q. ilex, scanning electron microscope investigations of pollen and hairs on the leaves of three species were made, on: Q. ilex L., Q. cerris L. and the »green oak«. Oak pollen is of elliptical shape and tricolpate. The ornamentation of the pollen grains of Q. cerris and the »green oak« were similar concerning the ornamentation of the exine – warty and rough and with small rounded protrusions – as well as the size of the pollen grain. Q. ilex pollen was much smaller and the surface lacked the small irregularly shaped protrusions typical of the other oaks. Within samples of holm oak pollen, significant difference in the surface structures was observed. Concerning the different types and number of hairs on the leaf surfaces, Q. ilex revealed a much greater number of stellate hairs on the upper leaf side as compared to Q. cerris and the »green oak«. Simple uniseriate hairs and simple unicellular hairs were missing on the leaves of Q. ilex, but were present on both the other oaks. To sum up the results, the »green oak« and Q. cerris reveal some similarities whereas Q. ilex does not.
HERMAPHRODITIC FLOWERING IN GAMBEL OAK
Gambel oak (Quercus gambelii Nutt.) is normally monoecious, flowering once a year in spring. In Utah, August 1978, several individuals were observed producing hermaphroditic flowers in riparian habitats. This unusual event was preceded by a general freeze of male catkins in May which resulted in low acorn production. In 1979 the same individuals flowered normally, with no evidence of freeze damage or hermaphroditic flowers being observed. Acorns were produced on these individuals in both years. It is suggested that hermaphroditic flowering in the Fagaceae is an ancestral condition, still present in the genome, but normally suppressed, which may be evoked by unusual environmental conditions. ON 2 August 1978, an unseasonal flush of flowering was discovered by R.P.N. and further observed by L.H.W. on several streamside clones of Gambel oak (Quercus gambelii Nutt.) near the mouth of Emigration Canyon near Salt Lake City, Utah, at 1,490 m elevation. This unusual phenomenon also was observed on streamside clones near Payson, Utah on 3 August at 1,460 m elevation. These inflorescences were unseasonal in that they had appeared late in summer (rather than in early spring) and had emerged from buds terminating twigs of the current season. Observations of these inflorescences were made during a general survey of Gambel oak in Utah to assess the impact of a spring freeze on acorn production. Oaks were examined in the range of habitats in which they occur (Neilson and Wullstein, 1980). On 9 August 1978, in situ examination of the inflorescences in Emigration Canyon by J.M.T. revealed an aberrant morphology similar to that described by Tucker (1972) for two species of oak occurring in California. The new flush appeared to consist of female inflorescences which were more elongated and bore many more flowers than normal. Most unusual of all, under a hand lens it was evident that some of the flowers in each inflorescence were hermaphroditic. We believe this is the first published report of this unusual event in Gambel oak. Although hybrids between Q. gambelii and Q. turbinella are known to occur in this area (Cottam, Tucker and Drobnick, 1959), all hermaphroditic I Received for publication 20 September 1979; revision accepted 23 April 1980. We thank Dr. Dov Koller of the University of Jerusalem at Rehovot for the suggestion of the bud removal experiment. flowers we observed occurred on clones judged not to be hybrid. In Q. gambelii normal female inflorescences are commonly 1 cm long or less (infrequently as much as 2 cm) and bear 1-4 flowers at anthesis, only 1 or 2 of these developing into mature acorns. As in the oaks generally, the female inflorescences are borne early in the growing season, in the axils of the upper leaves on young twigs of the current season (Turkel, Rebuck, and Grove, 1955). The male catkins, which appear in much greater numbers, emerge from lateral buds around the terminal bud or are borne at the base of the young elongating terminal shoot that will develop from the terminal bud. Although oaks generally flower in early spring, the flower buds are initiated the preceding year (Conrad, 1900; Turkel et al., 1955). In the shrubs observed in Emigration Canyon, the aberrant late summer inflorescences were borne in positions where next year's catkins are normally initiated, i.e. around the base of the new emerging shoot. Therefore, the aberrant inflorescences we observed in Emigration Canyon in August 1978 were initiated the same year, since they arose from buds terminating leafy twigs of this season. Thus their development, from initiation to anthesis, was compressed into a single season, a radical departure from the normal schedule of events. The inflorescence axes were stiff-not pendulous, as in male catkins-up to 3.2 cm in length and bore up to 14 flowers distributed more or less evenly along the length of the axis. Under a dissecting microscope, the flowers were seen to be mostly female but in each inflorescence at least a few flowers also contained stamens. On the longest inflorescence observed, the lowest four had the general appearance of female flowers (but each also con-
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.