Abstract

Olona, Touchardia latifolia, and ulu, Artocarpus altilis, both contain specialized cells called laticifers that have had significant and useful roles in Hawaiian ethnobotany. The first part of this study compared the origins, history, legends, and uses of these two plants. Research revealed that olona laticifers were used for fishing lines and other cordage purposes whereas ulu laticifers provided the Hawaiians with glue and caulking material. In the second part of the study, laticifers in olona and ulu were examined on a biological level. Laticifers differed between olona and ulu on a microscopic scale in distribution, size and shape, cell wall composition, contents, and location, and differed on a macroscopic scale in latex concentration, and extraction. This comparison of laticifer characteristics demonstrated why these specialized cells were used for such different ethnobotanical purposes in Hawaii.

Introduction

Olona, Touchardia latifolia, is a woody shrub endemic to Hawaii. Though a member of the Urticaceae, stinging nettle family, olona is free of stinging hairs and only occasionally pubescent. Young stems and petioles are light green and watery, breaking easily; mature stems have a thin to rough bronze-brown bark. Olona stems grow upright and are usually unbranched until they fall over. Patches growing wild often originate from a single stem, which sends new roots into the loose soil and sprouts branches on the upper side. Large ovate leaves with three distinct veins grow near the top of the stems (Figure 1a). Leaf morphology such as leaf color, pubescence, and redness of the midrib, varies from location to location. Plants are dioecious and the flowers grow in the leaf axils in tight spherical clusters. The five-parted male flowers have white stamen filaments and inconspicuous petals. Male inflorescences grow from elongated, branching peduncles. Female flowers are smaller, five-lobed, without conspicuous perianth, and grow in smaller, more compact clusters appressed to shorter peduncles than the male inflorescences. Fruits are bright to dull orange at maturity, fleshy, and contain a flattened teardrop shaped achene with a waxy, brittle seed coat and slightly winged margins (Wagner et al., 1990).

Figure 1a: Olona, Touchardia latifolia. Waiahole Valley, Oahu.

Handy and Handy (1972) reported that olona grows in "boggy interior valleys" and "upland areas" and Kamakau (1976) describes olona habitat as rainy, marshy, mossy, in mountainous areas, often near banana trees. Funk (1982), during sporadic field studies, confirmed the habit of olona to grow in wet areas with deep soil and reported that although elevation varied, olona preferred steep or disturbed terrain.

The ulu or breadfruit tree, Artocarpus altilis, in the Moraceae (fig) family, grows to be about 15-20 m, with smooth light colored bark and a hard yellow wood. Leaves are large and leathery, usually glossy (Figure 1b). Leaf morphology varies significantly in shape and depth of lobing. Flowers are dioecious, with both male and female inflorescences initiating from a terminal bud enclosed by two large stipules. Male flowers are tightly packed into an elongated inflorescence that emerges before the female inflorescence, which consists of 1500-2000 white flowers growing in a dense globular cluster terminating a single, thick peduncle. The female perianths expand and fuse to form the light green fruit, 12-20cm by 12cm large. The rind of the fruit is made up of disks, originally the flower surfaces, and thus ulu is a "multiple fruit". In varieties of Artocarpus found mainly in the western Pacific Islands, seeds 1-2cm thick are imbedded in the pulp of the fruit near the enlarged core (Ragone, 1997) but the variety introduced in Hawaii was seedless. Ulu roots can send up shoots when cut or damaged. Milky latex flows from wounds and coagulates upon contact with air.

Figure 1b: Ulu, Artocarpus altilis. University of Hawaii at Manoa, Oahu.

Though hardy, ulu grows best in consistent rainfall on equatorial lowlands or coastal plains. Hawaii is the northern limit of ulu, accounting for lower production than in other Pacific Islands (Ragone, 1997). Ulu fruits for 8months out of the year in Hawaii, primarily in January, June, and August.

The purpose of this study was two-fold. I wanted to first research the myths and legends associated with olona and ulu, their origins and early cultivation in Hawaii as well as harvesting techniques, and the ehtnobotanical uses of each in ancient Hawaii. I also hoped to make a statement about the current distribution and ecological status of olona and ulu in Hawaii. Second, I undertook a biological investigation of laticifers in both plants to help explain their ethnobotanical significance. For this purpose, I compared microscopic laticifer anatomy, lataex distibution, and ease of laticifer isolation.

For biological comparison of olona and ulu laticifers, fresh material was collected from field sites (olona) and UH campus (ulu). Leaves, petioles, peduncles, and stems of different ages from both plants were cut into 1cm pieces and immersed in antifreeze fixative of 10% dimethyl sulfoxide (DMSO), 1%Tween 20, 4%formaldehyde and 0.05M cacodylate buffer, pH 7.4. Within 24 hours of immersion, plant material was placed in a vacuum chamber for at least 24 hours. Material was stored in airtight vials and refrigerated until used. Sections 35-40 micrometers thick were made in a cryotome at -20° C. Laticifer distribution in the tissue, size and shape, contents and staining response (cell wall composition), and location throughout the plant was compared. Because laticifers are often difficult to recognize in cross section, I also made longitudinal sections of mature tissues to distinguish laticifers from other tissue types and compare their length and branching habits. Areas of high latex concentration were qualitatively determined by puncturing live plants in different areas and comparing latex flow.

Laticifers were isolated from fresh olona stems as per literature information on harvesting and retting. I chose stalk between 1.5 and 2 cm in diameter from a male population on the Lower Manoa Cliffs Trail on Roundtop. I cut the length of the straight stem with a knife, peeled the bast layer with my fingers and rolled the strips inside out. I soaked half of the strips in water for 24 hours and half for 72 hours. I scraped the strips using a plastic hand paddle and a pocket knife on a smooth stone surface and hung them to air dry.rips were hung to air dry.

Strips of ulu were soaked in water but could not be retted.

Only one legend was found involving olona: the story of the birth of Kamehameha. The babe was in danger of being seized by marauders, so was taken up into the hills of Kohala to be suckled by a woman who was scraping olona bark. A pile of olona fibers on the floor of her shed concealed Kamehameha from the enemy search party (Handy, 1972). One chant was found referring to olona cordage (Abbott, 1992).

Numerous legends are associated with ulu in Hawaii. To begin, the two morphologies found in Hawaii are supposed to represent the two sexes: the upright form, ulu-ku, symbolized the male, and the shrubby form, ulu-ha-papa, the female (Beckwith, 1970). The best-known origin myth comes from Tahiti. The god Ku feared his family would starve to death during a famine, so he asked his wife to slay him and plant his body parts in the front yard. The next day, a breadfruit tree stood in the place of his head. After his family had eaten their fill, the breadfruit continued to produce and feed the rest of the community. Another origin myth involves two fishermen from Pu'uloa who were blown to Kane-huna-moku, the "mythical land of Kane" (Handy, 1972), and returned bearing a fruit tree (Beckwith, 1970) that propagated ai kameha'i, by the will of the gods (vegetatively) (Handy, 1972). The more rational story of ulu transport to Hawaii is that Kaha'i, son of Ho'okamali'i, grandson of Moikeha, brought breadfruit from Upolo, the Hawaiian word for a Tahitian valley and for Samoa. Kaha'i planted ulu on the southern coast of Oahu, in the Ewa district near Pu'uloa. In a later myth, which has many versions, the goddess Haumea rescues her husband from which has many versions, the goddess Haumea rescues her husband from kidnappers and passes through a breadfruit tree. The pursuers try to cut down the ulu tree, but flying splinters and the milky sap kill the woodcutters. After making sacrifice to the ulu, the kidnappers are allowed to carve the ulu tree into a goddess, whom Haumea names Kamehaikana (Westervelt, 1963). One other ulu myth concerns Kaulula'au, son of Kaka'alaneo and Kanikani'ula on Maui, who pulls up breadfruit as a prank. He is sent to a haunted island by his father, but courageously tricks the spirits and saves himself (Beckwith, 1970). There are a number of sayings also associated with ulu, the most famous of which is "go for the breadfruit that oozes gum" which tells a young girl to look for a rich husband (Handy, 1972).

The first discovery and use of olona by Hawaiians is unknown. Because, as Kamakau mentioned, there are very few suitable places for large plantings of olona, it was grown in small patches, though olona has been known to grow in fields up to 2 acres large (Krauss, 1993). Different types of patches had different names. A large cultivated patch was olona kihapai; a garden patch was olona mala; and a wild clump was opu olona (Summers, 1990). Stalks were encouraged to grow straight and tall, "as alike as hairs on the head" (Kamakau, 1976), and close to one another to reduce branching (Krauss, 1993). Lateral branches were removed from upright stems to reduce the number of holes in the bast fiber (Summers, 1990). Old stalks or toppled stalks were bent to the ground and covered with soil to promote rooting and lateral branching to form new stalks. Finally, Hawaiians weeded frequently, for olona has a tendency to get choked out (Krauss, 1993).

Handy (1972) states that olona was "one of the few plants native to the islands that were utilized by the Hawaiians". Actually, ancient Hawaiians used many endemic, but Handy may have singled out olona because it became prized as a trade commodity with European explorers. J. Smith (1902) was excited by the prospects for a plant that produced, in his opinion, a large fiber yield per plant and per area. Despite this potential, extensive cultivation of olona ended probably around the time when the prized cordage was replaced with nylon fishing line and other synthetic materials.

Ulu originates from a wild form domesticated in New Guinea and the Bismarck Archipelago and spread throughout the Pacific Islands by the first Polynesians. Fijians and Samoans cultivated the seedless variety, A. altilis, popular in Remote Oceania. Since European discovery in the 1600's, breadfruit has extended all the way to Africa and across South America (Ragone, 1997). The seeds lose their viability quickly when dry, so ulu was most likely transported as root cuttings. However, ulu is not very resistant to salt water (Ragone, 1997) and requires a ball of dirt and special care. Handy (1972) commented that the introduction process couldn't have been easy. The importance of ulu fruit as a food staple compensated for the trouble, however. Ulu was most likely introduced to Hawaii from Tahiti (Handy, 1940), although it may also have arrived with the Islands' first Polynesian settlers who came from Marquesas. Unlike olona, ulu was never in high demand in Hawaii, and breadfruit was of secondary food importance to taro and sweet potato. Therefore, ulu was not incorporated intensively into mixed cropping, and was found primarily in backyards, as it is today. Like olona, ulu is cultivated via vegetative propagation. An ulu tree begins fruiting after three to five years, and will produce with little upkeep for over to 35 years (Abbott, 1992).

The age of the olona stalk made a difference in harvesting time. Plants around 18 months were preferred for retting because the bast fiber of older stalks is too knotty. The bast layer was easily stripped off straight stalks with the fingers (Kamakau, 1976). Strips of bark were carried over the shoulder or rolled with the bark inside to flatten them out (Abbott, 1992). Most accounts report that the strips of bark were softened in water, sometimes running water, for a day or so, but natives interviewed by Dr. N. Russel (Smith, 1902) omit this step. Sheds were erected near olona patches for scraping down the harvested bast fiber (Handy, 1972). Both sides of the bast fiber layer were scraped down on long, thin hardwood boards called la'au kahi olona or papa olona. The scraper was usually a sea shell, though later turtle bone from the costal plate of the shell was used. The scraper was sharpened frequently. Russel claims that scraping was completed in 1-2 minutes, leading him to advocate large scale production of the fiber-yielding plant. However, Summers (1990) implies that practice was required to master olona scraping: only experts could scrape a few hundred strips in a day. The white ribbons of fibers (actually laticifers) remaining were separated with the fingernail, dried, and twisted into cordage by the women (Handy, 1972)

Olona cordage was prized because of its resistance to kinking and to many other conditions (Handy, 1972). Fish lines could be few or many-ply, and were often heavy, but always very strong. One fish line was reported to be 250-295 meters long (Summers, 1990). Other types of fish lines often used olona fishhook leaders. Olona cordage was popular in making nets, including fishnets, 'upena, and carrying nets, koko. Fine cordage used for the netted matrix in feathered helmets and capes averaging 0.6mm in diameter. Olona was also used to repair cracked gourds and canoe paddles, and attach two pieces of a fishhook together or bind a stone adz to its handle. Other uses included stretching drumskins over drums and tying the umbilical cord (Summers, 1990).

The ulu fruit is ready to eat when the sap oozes out over the skin. Hawaiians preferred their ulu a little riper than other Polynesians. Hawaiians used the fruit in a number of ways, though not with as much variety as found elsewhere in the Pacific. The most common food preparations included roasting, wrapping in ti leaves and baking in an imu or earth oven, pounding into poi ulu, or mashing with coconut cream. Ulu wood was used for house frames, shortboard surfboards, and could be hollowed into drums (Abbott, 1992). Dried stipules were used to polish kukui nuts and wooden bowls.

The ulu latex, kepau, had a variety of uses in Hawaii. In some Pacific islands at least, the trunk is cut in the morning and the sap collected later in the day (Ragone, 1997), although Abbott (1992) says the stem of the fruit was also a source of the milky sap. Kepau served as a watertight caulking material for canoes, a glue for joining double gourds used as drums in hula, gluing or coating pieces of kapa, or setting shark's teeth in war clubs (Krauss, 1993), and for repairing wooden objects (Abbott, 1992). Ulu latex was spread on tree branches as birdlime to trap birds for feather gathering. Children chewed the dried sap like gum. The latex also had medicinal uses. For ulcers and skin sores, kepau was mixed with pounded, roasted kukui nuts and pulverized lama wood and pressed into makaloa (Cyperus laevigatus) fibers for a compress. 'Ea, or thrush, a fungal disease of the mouth, was treated with a poultice of ulu leaf buds and 'alaea, or red dirt loaded with ferrous oxide. This salve was followed by eating a small green fish called aeaea. Theobald (1976) believes the curative effect of ulu on 'ea is related to the latex present in leaf buds and young growth.

Current status of olona in Hawaii is unknown. No single researcher or crew has catalogued wild sites on all islands, although Funk has informally explored Oahu, Kauai, and Maui, and other scientists have located specific sites on Oahu. When I explored the areas near Manoa and Waiahole, I found fewer plants than reported in previous field excursions. The plants grew tenuously in loose or disturbed soil, frequently accessible only with great difficulty. Olona was often found growing among an introduced Rubus species, which tends to outcrowd less competative plants, a common downfall of endemic species. My limited field experience leads me to believe that without human intervention of some sort, olona may soon be rare.

Ulu is often found in residential backyards, but also grows in arboreta throughout Hawaii, and on UH Manoa campus. As an introduced species, 'ulu has never grown wild; trees that appear feral are actually vegetative ancestors or suckers from trees from an orchard garden agricultural system. I do not fear for its longevity.

Laticifers, though sometimes confused with fibers, do not share all characteristics with them. Whereas fibers are long tapering cells with thick walls and pits and are often found in groups, laticifers have thin or irregularly thickened primary cell walls, often contain latex, and are found in groups or individually, often associated with vascular tissues (Funk, 1979, Mahlberg, 1993). Laticifers may be articulated (having sections) or unarticulated (entire), branched or unbranched. They develop early in the embryo of a plant, and elongate by intrusive growth that keeps pace with the surrounding tissue. Laticifers are usually larger in diameter than neighboring cells, and may be pitted. They are not found in primitive angiosperms and are harder to see in the root than other parts of plants that contain them (Mahlberg, 1993). Laticifers in olona are unusual for their very thick cell walls and great strength (Funk, 1979).

Distribution of laticifers in cross section

Olona laticifers were found in the cortex of the stem usually clustered near the phloem (Figure 2a). The laticifers are distributed evenly in the middle of the cortex, sometimes up to five cells deep, although rarely in dense clusters (Figure 2b). Laticifers were not present in the pith.

a.

b.

Figure 2: Cross section of olona stem showing distribution of laticifers. a: laticifers (L) distributed in cortex between epidermis (E) and phloem (P). Stained with toluidine blue; 40x. b: laticifers (L) may be many cells deep. Viewed with polarizing filters; 40x.

Like olona, ulu laticifers are present in the cortex (Figure 3a), but unlike olona, they are also present in small numbers in the pith (Figure 3b), and didn't seem as distinctly associated with vascular tissues. In the cortex the laticifers are scattered throughout the collenchymous area under the epidermis as well as in the region with larger-celled parenchyma (Figure 3c). Fresh sections of ulu mature peduncle contained large groups of latex-filled cells of various diameter (Figure3d), indicating that the latex leached out of the preserved material, making the laticifers hard to find

a.	b.		Figure 3 a: laticifers (arrows) in cortex outside vascular tissue (V) in young woody stem. 25x. b: laticifers (arrows) in pith inside xylem tissue (X) in young woody stem. 40x.
c.	d.		c: laticifers (arrows) in both collenchyma (C) and parenchyma (P) of cortex in leaf midrib. Stained with toluidine blue; 50x. d: group of laticifers (circled) in cortex of mature peduncle. Fresh material.

Size and shape

Olona laticifers, when developed, are large cells with unevenly thickened cell walls. These laticifer cells are usually larger in diameter than their surrounding cells, irregularly shaped, and have thick primary cell walls. The cell wall thickens in sections, making the wall look pitted (Figure 4a). Laticifers are more or less linear, following the growth of the stalk, as seen in longitudinal section (Figure 4b). Laticifers are unbranched, unarticulated and have tapered ends.

a.

b.

Figure 4: Size and shape of olona laticifers in stem. a: cross section showing laticifers (L) with unevenly thickened cell walls. Courtesy of Dr. Webb. b: longitudinal section with unbranched, unarticulated laticifers (arrows). Partial polarizing filter; 25x.

Ulu laticifers are not as distinctive as olona laticifers. The cell walls of ulu laticifers are similar to those of the surrounding parenchyma (Figure 5a). They are unarticulated in the cortex and leaf mesophyll (Figure 5b), but may also be articulated in the pith (Figure 5c). The unarticulated laticifer cells are generally circular in transverse sections because they grow by intrusion between cells (Mauseth, 1997). Therefore, in transverse section, they appear round and surrounded by slight angular thickenings of the cell wall, perhaps to fill in between them and neighbor cells (Figure 5d). Longitudinal sections revealed that some of the laticifers have short branches, and meander through the tissue rather than parallel to axis of growth (Figure 5e). Finally, the laticifers are not as long as olona laticifers and have blunt tips.

a.	b.		Figure 5 a. cross section of young woody stem showing content-containing cells and laticifers (arrows) with uniformly thickened cell walls. 100x. b. unarticulated laticifers in woody stem, subtended by dashed lines. Stained with IKI; 25x.
c.	d. e.		c. longitudinal section through pith of young woody stem showing column of latex-containing cells. 63x. d. cross section through pith of young petiole showing cangular thickenings between laticiters and adjacent parenchyma cells. Stained with toluidine blue; 160x. e. longitudinal section through unarticulated, branched laticifer (between arrows) near epidermis of young woody stem. 25x.

Contents and composition

Olona laticifers appear to have no specialized contents, although the entire section was loaded with amyloplasts (Figure 6a). Olona laticifers stained pink in toluidine blue, indicating pectins and cellulose. They are also highly birefringent when viewed with polarizing filters (Figure 6b).

a.		Figure 6 a: laticifers (L) take up toluidine blue stain. Laticifers appear empty but surrounding parenchyma is loaded with amyloplasts (arrows). Partial polarizing filters; 63x.
b.		b: longitudinal section showing laticifers (arrows) birefringent in polarizing filters. 25x.

The contents of ulu laticifers (unarticulated) and cell columns (articulated) were primarily either a pale yellow grainy substance with occasional larger globs or larger globules that stained very dark blue in toluidine blue (Figure 7a and 5d). To differentiate between latex and other cellular substances, I investigated the contents of fresh sections. The white substance oozing from freshly cut ulu was composed of small uniform grains or globs that sometimes coagulated into larger globs. The liquid matrix of the exudate coalesced under the microscope into a netlike mass with a stringy consistency. Only the elongated cells contained this substance. I concluded that the latex is a grainy substance with a matrix of rubber components (Mauseth, 1997). The grainy globs are not birefringent through a polarizing filter (Figure 7b) and did not take up stain, indicating a substance other than starch and crystals. Some cell contents in the leaf midrib stained golden with IKI. Those contents and the dark-staining contents of cell columns in the vascular system (Figure 7c) may be other secondary metabolites such as tannins (Mauseth, 1997). Ulu laticifer cell walls did not take up stains preferentially.

a.	b.		Figure 7: Contents of ulu laticifers. a: laticifers (arrows) contain uniform grainy substance. Cortex and vascular tissue of young petiole stained with toluidine blue; 25x. b: crystals are birefringent with polarizing filters, but laticifer contents are not. Section as in 7.a.
c.			c: articulated laticifers and columns of cells containing dark-staining substance in pith of woody stem. Stained with toluidine blue; 25x.

Laticifer distribution throughout the plant

The young petiole of olona contained no obvious laticifers. Aside from excessive collenchyma just under the epidermis and the vascular bundles, all cell walls are about the same thickness. In the young petiole from ulu, the laticifers are scattered throughout the section (see Figure 7).

In a cross section of the young olona stem 1cm in diameter laticifers were easily distinguished in the cortex between the epidermis and the phloem. A longitudinal section of this stem tissue revealed long laticifer cells in different stages of maturity. A young woody ulu stem 3/4cm diameter contained the laticifers observed in the petiole, but the pith also displayed other cells with contents mentioned above.

Olona appeared to have no laticifers in the midrib or blade of the mature leaf. Ulu, however, had a complex distribution of laticifers in these organs. As in the mature stem, latex-containing cells were slightly more frequent near vascular tissues of the leaf midrib, i.e. near the phloem fibers if in the cortex, and near the xylem if in the pith. Elongated, branched laticifers were present in the mesophyll of the leaf blade (Figure 8a). Some large latex-containing cells varying in size and shape were hanging suspended from the mesophyll the large air spaces between vascular bundles (Figure 8b).

a.		Figure 8: Distribution of laticifers throughout the ulu plant. a: unarticulated, meandering and branched laticifers (arrows) in mature leaf. 32x.
b.		b: latex-containing cells (arrows) suspended in air spaces of mature leaf. 63x.

In very mature ulu tissues, e.g. the outer layers of a branch 7.5cm in diameter, the heavy distribution of laticifers was especially evident in a thick section (Figure 8c). Though not examined in this investigation, the fruit should also contain laticifers because the rind oozes latex during the ripening process.

Figure 8c: frequent distribution of laticifers (circled) in very woody stem. Thick section.

Latex distribution within plant

Qualitative comparison of relative latex concentration among different plant parts within ulu as conducted between 7:30 and 9:00 am in full sun in mid-October on two plants on UH Manoa campus. When I broke a mature leaf off near the stem, the wound oozed 24 drops of a whitish fluid (Figure 9). Slicing off the stem apical meristem (immature stipules and terminal bud), produced 22 drops in the same amount of time. When examined later, the white substance had congealed on the cut surface to the consistency of rubber cement. I then made a slice 2cm long into a trunk 17cm in diameter 1m above the ground. The cut immediately oozed the whitish fluid. As it dribbled down the trunk, a thick opaque white component separated out from the milky liquid part and stuck to the bark in clumps. For some time one corner of the cut continued to ooze a thick white sap that emerged in spurts like bubbles and congealed upon contact with air. I scraped my knife tip across the length of the cut occasionally, removing a tan-white film with a consistency resembling rubber cement. I set it aside as I continued to remove it; the glob remained workable and sticky, like chewing gum. I concluded that younger tissue has higher liquid:congealant ratio in its latex, although even the rather clear liquid component was tacky.

Figure 9: ulu latex dripping from broken petiole.

A cut 2m above ground in an older tree 116cm in diameter oozed about the same amount of sap as the smaller trunk, but the oozing did not persist. The amount of white component was extruded in higher proportion than in the younger trunk, however. Simply inserting my knife 1/2-1cm into the trunk yielded much more latex than the shallow cuts. Letting the latex run down the bark or constantly scraping it off seems an inefficient means of collecting the sap; I wondered what was the traditional collection method. I made a makeshift collection method by inserting a strip of palm frond in the cut. The sap quickly flowed down and off the frond and could be easily collected. Latex from the deep cuts was very runny and didn't congeal to the same thickness as that from the younger trunk, but was still very tacky.

Old wounds in the mature tree had oozed latex some time earlier and dried into brittle grayish globs. I scraped off the thin gray bark and thin red underlayer from the older tree to reveal the pulpy orange wood. A thin sheen of latex slowly collected on the scraped area. When I cut 1/2cm further into the wood the latex dripped out quickly. I concluded that the sap-containing cells or ducts are located in the mature woody tissues under the bark.

Finally, I observed the flow of latex from a mature peduncle at 4:00pm in full sun on November 13. When I cut it near the top of the fruit, the latex spurted out with more force than any other organ I had tested.

Acetone was the best solvent for cleaning hands and instruments after dealing with ulu and its latex.

Olona tissues exude a clear watery liquid when wounded although the flow is not maintained after the initial few drops. Field observations indicate that young and herbaceous tissues such as petioles and leaves contain more fluid than woody tissues in the middle and mature stem region. The exudate is not sticky and does not harden or congeal upon exposure to air, but rather resembles contents of vascular tissues in other plants.

Isolation of laticifers

Although the bast layer was easy to remove from olona (Figure 10a), preliminary extraction of laticifer strands yielded disappointing results. During scraping, I alternately used the plastic paddle angled toward me, and the knife, angled away from me (Figure 10b). I found that it helped to keep the strip and area very wet with water. The leaf scars were difficult to scrape over, and created curves and holes in otherwise straight grain of the bast fibers. I was left with a greenish brown band of fibers that dried to a hard, curly, inseparable strip.

> a.

b.

Figure 10: Isolation of laticifers from olona. a: stripping the bast layer. b: scraping the bast layer.

The strips that had soaked for 72 hours, however, were more easily retted. The strips looked and smelled a little fermented when I removed them from the water, and the outer bark and inner pithy layer slid off easily using only the plastic paddle. Much of the fibrous material came off along with the bark and pith, so that what fibrous material remained was a very thin layer only about 1/2 the original length of the strips. The fibrous material was pure white as mentioned in the literature, and could be separated into individual strands or cells using only my fingernail. The strands were very strong, resisted tearing and breaking, and clung to one another as if their surfaces were rough. Once isolated, the strands hung straight and dried almost instantly without shrinking. After several days of air drying, the strands, which were finer than human hair, were still pliable, separable, and lightweight, and did feel slightly rough when pulled between two fingers. Of these strands, which seemed more suitable for cordage than those from my first attempt, the average length was 27cm, but some individual strands were over 45cm long.

Ulu outer layer was not easily distinguishable or separable from the rest of the woody growth in the trunk. Soaking in water did not soften the material at all: after three days the bast layer was still tough and cohesive. Scraping merely broke the woody fibrous tissue or pulled it apart in large clumps. The outer bark did not come off easily and the layer was so thick (0.5cm) that no laticifer layer could be discerned nor individual strands isolated.