Ptrlltttarta A PHOTOGRAPHIC STUDY Dedication This works is dedicated to the serious student and researcher who wishes to learn more of the Genus Hoya. It is hpjp&l it may lend additional data for pollen researchers in other Asclepiad genera and species. Mostly it is in appreciation of the intricacies of any study and the realization that no subject is simple once an in-depth inquiry is started. I wish to again thank all who have contributed of material and time to further my work in this field, their concern and helpful criticism is always aonreciated. J Printed and published at Fresno California USA 5 January 1996 by Dale Kloppenburg 6427 N. Fruit Ave. Fresno CA 93711 Copyright © All Rights Reserved ,,rtfie potCen masses present great variations in size, form, and length of pedicels and proSaBfy afford e?(ceC(ent characters". J. <D. Hoofer1838 in Flora of British India. Table of Contents Subject Page Dedication ii Statement Introduction Acknowledgments vi Materials & Methods Pollinarium Formation 3 Corona of Hoya 6 Stylar Table 7 Coronal Section 8 Labeled Pollinarium 9 Pollen Germination 10 Translator & Caudicle Development 11 Retinaculum 13 Pollinaria Develop. Stages 15 Terminology History 19 Measuring gauge 22 Pollinaria of 1 Flower 24 Pollinaria 5 years 26 Pollinaria different locations 29 Scanned Photos 31 Sect. Rudimentalia 32 Other Large Pollinaria 36 Pollinaria 0.75 mm. long 46 Sect. Acanthostemma 84 Verticillata types 114 Camosa Complex 127 Sect. Otostemma 134 Sect. Amblyostemma 141 Controversial species 151 Philippine palmate If. sp. 166 Short lull Pollinia 179 Hoya odorata etc. 196 Hoya australis complex 206 Hoya cumingiana etc. 213 Sect. Peltostemma 118 More sp. + unident. 224 Sect. Eriostemma 241 Sect. Physostelma 249 Glossary of Terms 251 Index of Photos 257 iv Introduction As with previous publications of mine, I hope the material and data herein contained will form the basis for a better appreciation of the Hoya pollinaria as a taxonomic tool. My first motivation in the direction came from Hooker’s profound observation of the stability of pollen masses while working with dried material (herbarium sheets). Secondarily, adverse criticism of Dr. Rintz’s emphasis on the past neglect of “twin- pollinia” as a taxonomic character, spurred me on to further critical in-depth study. Dr. Schlechter drew floral parts on most of his Hoya herbarium sheets. Drawings of the pollinarium were also included. Although these representations are small and lacking in many details, they are none-the-less valuable in re-identifying his species as their relative proportions are still of value. Even in his descriptions, such comments as “retinaculum very small” are significant in a taxonomic sense. The most detailed drawings of Hoya pollinarium have been those of David Kleijn of the Netherlands. David Liddle in Australian publications has also made detailed drawings of Pollinarium. I have one objection to the positioning of the Retinaculum above the two pollinia by these two authors and by Dr. Rintz. To me it is like not using the top of a map to represent north. The pollinarium in Hoya is upright, i.e. the retinaculum is secreted by the fused stigmas and the pollinia are inward toward the center of the flower. For me, Schlechter had it correct! I have discussed under “Materials and Methods” some of the difficulties in photographing these very small structures. There is a loss of resolution and detail at every step of the process in bringing this work to publication. I suppose we all wish for more money, better equipment, and above all more time. The expenses and time of all this work is borne by me personally. Many thousands of negatives and pictures have been filed and labeled. These form the data base for this and further studies. I feel a photographic record is invaluable, since at any time I can refer back to the actual photo. I continually re-photograph species so I am able to study any variations occurring over time. In addition, clones bloomed in many locations are added to the photographic and data record on a continuing basis, along with drawings and critical measurements. With the advent of computers it is easy to make necessary corrections and additions to a data base and to then from time to time release updated publications. Acknowledgments Tlie development aiul wnting of this book required the help of a large number of people Probably die most important are all those who took time to send me flowers and cuttings In addition constructive comments have been invaluable in furthering nnLW°t,h T!rS »,e bee" USed in my Photographic data base of hoya species. For ^"Wran (^W) °reg0n> Ted Green (T°) Hawaii, Chanin Thorut (CT) Thailand Michael Miyashiro (MW) and Jerry Williams, Vista Ca The above have also provided innumerable cuttings. In addition cuttings have been supplied by Hem" H*usch£el1 (DH;), Professor Juan Pancho (JP), Maximo Wayet (MW) Blass of^M^"1 ,the.Ph'1'Pplnes'the late Pe‘er Tsang of Australia, Ruurd van Donklaar of the Netherlands Ins and David Liddle of Australia, and Geoff Dennis " * c“ «■« - «■ fndir6 S,‘aff 3t ** University of California Beikeley, California USA 2'fate %(oppen6urg P Materials and Methods olliniaria of the Hoya flower are very small but the five dark brown colored retinacula are readily visible in the crown without the aid of magnification. In working to remove the pollinarium I use a “Swift” binocular microscope with 10X magnification. With the sharp end of a fine sewing needle inserted under the outer end of the retinaculum, a gentle lift will usually release the entire structure intact. Those removed are placed on a slide with a 1 mm. imbedded graduated scale, as a measuring device, divided into microns (100 parts). The slide is wetted with a drop of Kew solution (glycerin, water, and formaldehyde). The removed pollinaria are easily transfer to the wetted area. Most pollinarium can be examined at thirty power or above. At around 30-40 magnifications the pollinarium are easy to focus since the field depth is relatively small. An overall view is good at these magnifications. I have found that a magnification of 100 power is best for detailed study of most hoya pollinarium. For this I use a Bausch & Lomb monocular scope. It is provided with a EW 10 XD/20.50 -14.5 mm. eyepiece. The lOx lens is 0.25. By the time the pollinarium is in good general focus in a SLR camera the magnification with this lens combination is approximately 160X (actually it is slightly more than 162). The camera is provided with a microscope adapter which allows me to switch from the Swift binocular scope (for extraction) to the monocular for measurements and photography. The camera mounts on the eyepiece, and the SLR feature allows visual focusing through the microscopes. Problems encountered: At near 100X magnification even though the pollinarium is a small object (we are dealing with fractions of a millimeter) the depth through which you must focus becomes greater (the depth of field is shallower). This requires a number of photos at various focal planes to record all the features. Thus presentations must be of a number of photos or composites. The retinaculum is especially deep i.e. three dimensional and thick, especially at the head and central portion. The photos (copies) in the data pages are a best average photo depiction of the structure or a composite in a few cases. At 160 magnifications some pollinarium are too large to fit within the view area and thus must be a composite of at least two photographs. Problem areas in addition to the above are: (1) When removing pollinarium, both pollinia do not always stay adhered to the caudicle. In some instances neither of the two pollinia may remain attached. The longer the flower is open the more this becomes true. (2) Occasionally, especially from herbarium material, the pollinia may be withered (not the general situation). Preserved dry flowers must be thoroughly soaked in Kew solution (or boiled) before removal is practical. (3) Destruction of the pollinia (since it represents high protein) by bupestids or other insects is occasionally encountered. (4) Upon extraction from the anthers the pollinia and retinaculum often twist and turn. This is especially true of translators located well down the retinacular column. It becomes a real challenge to get them to lie in their original configuration, and flat on the slide. Long retinaculum with the translators attached well down on the column tend to raise their head (the inner apex) above the scale surface, adding to the depth of the focal plane. This adds to the difficulty of getting a single clear photo of die structure. In some cases the twisting is almost impossible to undo. Ehying the slide is an aid and using two needles for manipulation helps. The poflinarium of course can be studied from the top (normal positioning) or turned on its back and studied from the bottom. I have been using 100 ASA color film or recently 200 ASA speed color film. The faster speed film cuts down on the exposure time (and thus camera battery renewal). I at first used the auto exposure meter of the camera but learned that most photos were overexposed (more true for floral parts than of the pollinarium through the monocular scope). With a tensor lamp directly below the stage, directed up through the field it takes only a fraction of a second for full exposure, possibly 1 second I now use the bulb camera setting. Photos show more and clearer detail then the photocopies or scanned images presented here but are too expensive to use in this presentation. 2