Yagrumo Macho

Didymopanax morototoni (Aubl.) Decne. & Planch. Yagrumo Macho Araliaceae Ginseng family L. H. Liegel Yagrumo macho (Didymopanax morototoni) is a Soils and Topography well-known pioneer species throughout the tropical Americas. In commerce, the common name is Yagrumo macho is not exacting in soil require- morototo or matchwood because the wood is used for ments. Therefore, it grows well on a variety of soils, match splints in several countries. The light weight especially those that have been abandoned after wood is also substituted for certain grades of balsa. agricultural use. In Trinidad, stands are found on flat areas having deep, bleached sands (Entisols) and on gently undulating areas having outcrops of acidic Habitat clays (Ultisols or Inceptisols) (2,19). In Puerto Rico the species grows most commonly on either deep or shallow acid clays (Ultisols and Inceptisols) in the Native Range mountains or on calcareous soils (Mollisols) in the “haystack” (mogote) limestone hills. Yagrumo macho is the most widely distributed Although yagrumo macho grows on flat areas in species within the genus Didymopanax. The range is Puerto Rico, particularly near streams, it is more (17) extensive, roughly from latitude 17” N. to 25” S., and predominant in upland dissected terrain from covers wet and moist forests of the West Indies, from 100 to 900 m (330 to 2,950 ft); slopes are usually 45 Cuba to Trinidad, and continental tropical America percent or more. On the western end of Puerto Rico, from the States of Oaxaca and Veracruz in Mexico, it grows almost at sea level (21). The highest eleva- through Colombia, Venezuela, the Guianas, Brazil, tions reported for yagrumo macho are in Colombia, and Argentina (4,12,X,23,25,26,33). The species was where it can be found from 500 to 1700 m (1,640 to 5,580 fi) (28). introduced to Jamaica and has been planted in southern Florida. In Puerto Rico it is quite common, growing in over half of the municipalities and in 8 of Associated Forest Cover 13 State Forests, but it is not common anywhere else in its range. In Panama it is reportedly more abun- Throughout its range yagrumo macho is a common dant on the Pacific side than on the Atlantic side. species in secondary forests, in natural or man-made Local or regional range maps are known only for openings in mature forests, or along roadsides and Colombia and Puerto Rico (13,16,28). river banks. In Puerto Rico’s Subtropical Wet Forest it is often associated with yagrumo hembra or trum- pet-tree (Cecropia peltata) and guano or balsa Climate (Ochroma pyramidale), which are also fast-growing, large-leafed successional species having similar physiognomies (10). In openings caused by blow- In Puerto Rico yagrumo macho grows in Subtropi- downs it is also associated with tabonuco (Dacryodes cal Moist, Subtropical Wet, and Subtropical Rain excel@, the mature component in natural remnants Forest life zones (10). Mean annual temperatures in of the Subtropical Wet Forest in Puerto Rico. these life zones range from 24” to 26” C (75” to 79” In the State of Oaxaca, Mexico, yagrumo macho F), 22” to 24” C (72” to 75” F), and 22” to 23” C (72” grows with other thicket species like pegoge (Taber- to 73” F) with mean annual precipitation of roughly naemontana arborea), mata-raton (Gliricidia 1500, 3000, and 4000 mm (60, 120, and 160 in), sepium), Vernonia patens, Acacia globulifera, respectively. Elsewhere, yagrumo macho grows in camasey (Miconia spp.), Belotia cambellii, and cerezo similar life zones, and mean annual precipitation (Cordia glabra) (32). Three locally important and as- may exceed 5000 mm (200 in) in some parts of the range, as in Colombia (28). sociated hardwood species in Trinidad are gommier (Protea insigne), Sterculia caribaea, and serette (Byr- sonima spicata) (2). In Venezuela yagrumo macho The author is Soil Scientist, Pacific Northwest Research Station, and yagrumo hembra form a transition zone between Portland, OR. (Research on this species was done in cooperation guaba (Inga spp.) stands growing along the rivers with the University of Puerto Rico, Rio Piedras.) and high forest stands of Parkia pendula occurring 288 Didymopanax morototoni further inland (34). In the Bajo Atrato region of seeds is quite small and germination is extremely Colombia it is associated with Simarouba spp., box- poor. Of over 800 individual seeds collected at one wood (Jacaranda copaia), and Schizolobium site in Puerto Rico, only 5 were viable (21). parahybum (20,22). Highest germination percentages recorded were 30 percent after 70 days in Brazil and 35 percent after Life History 40 to 90 days in Costa Rica. In Brazil the seeds were soaked for 9 to 10 hours in an unspecified chemical, Reproduction and Early Growth covered with a thin layer of soil, and protected from direct sunlight. Seeds in Costa Rica were treated Flowering and Fruiting-Yagrumo macho has with a 3 percent solution of sodium hypochlorite (21). perfect flowers and reproduces in a yearly cycle. Of After germination periods of 52 to 120 days, only 12 96 trees observed for 14 months between 1976 and of 300 seeds germinated in three trials in Puerto 1977 in the Luquillo Mountains and at the Rio Rico. Several soaking treatments with 9 iV sulfuric Piedras Agricultural Experiment Station in Puerto acid were used. Old records from Trinidad show that Rico, 58 flowered mainly from October through treating with unknown plant hormone solutions and December (21). There was significantly less flowering human urine aided seed germination. in other months. Minimum sizes of trees producing Some 16 bird species feed on yagrumo macho seed fruits were 6.4 m (21 ft) tall and 10.2 cm (4 in> in or fruits in Puerto Rico. This may provide a plausible d.b.h. In Trinidad, flowers have been observed main- reason why good germination in the field cannot be ly in October but also in April and September (19). duplicated in laboratory or nursery conditions. Information on flowering in other countries is not Studies have shown that after seeds are ingested by available, but with yagrumo macho’s rather extended birds, they are subjected to scarification in the giz- range, great latitudinal variation in flowering and zard and chemical treatment by gastric juices in the fruiting can be expected. Flowers are numerous and stomach (20). Although attempts to germinate seeds grouped at ends of branches into many rounded taken from bird feces have failed in Puerto Rico, they clusters, from 0.3 to 0.6 m (1 to 2 ft) long. The 5 have been successful in Costa Rica. It is also petaled, fine brownish and gray hairy flowers are proposed that some species feed only on the outer about 5.0 mm (0.2 in) across, with white petals about coat of yagrumo macho seed and others feed on the 1.5 mm (0.06 in) long, and five stamens and two seed endosperm. Thus dormancy could be broken by styles (16,21). mechanical puncturing or breaking of the seed coat. Pollination mechanisms have not been studied in Until further evidence is gathered, it can be assumed detail. Bees of the Tkigona and Mellipona genera that birds play the primary role in germination and have been observed on yagrumo macho flowers in dissemination of yagrumo macho seed. In Trinidad, Costa Rica. Ants of the Crematoguster genus may bats also act as dispersal agents (3). also play a role. Yagrumo macho seed is unwinged and heavy. Of It takes approximately 1 to 2 months for flowers 341 fruits and 125 individual seeds collected beneath to develop into fruits. Immature fruits are dark green or deep purple. They are fleshy, 4 to 6 mm (0.16 to one tree in Puerto Rico, all came from one quadrant 0.24 in) long, 7 to 10 mm (0.28 to 0.39 in) wide, and around the tree’s base. about 2 mm (0.08 in) thick. Fruits usually contain two and occasionally three oblong and flattened Seedling Development-Germination is epi- brown seeds, about 5 mm (0.2 in) long. Mature fruits geous. Few studies document seedling growth of are dropped almost every month in Puerto Rico, but yagrumo macho in either field or nursery conditions. production peaks from November through June (21). Early growth is fairly rapid and best when seedlings In Costa Rica fruits mature in January and fall from are exposed to direct sunlight. In Brazil, d.b.h. and February through May. height mean annual increments (MAI’s) were 3.0 cm (1.2 in) and 1.7 m (5.6 ft) for 2-year-old plantations Seed Production and Dissemination-Seed (5). A 7-year-old plantation had mean annual height production for yagrumo macho is an almost con- and d.b.h. increments of 1.7 m (5.6 ft) and 19 mm tinuous process, as it is for other successional (0.8 in). A 20-month-old plantation in Bajo Atrato species. Seeds have a hard, impermeable outer coat; region of Colombia, planted at 3- by 3-m (9% by they can thus remain on the ground for a long time 9%ft) spacing, had very good form and fine branch- and still retain viability to germinate when openings ing, with a branch angle usually greater than 70”. in the canopy occur. When seed is collected and taken Height and d.b.h. averaged 8 m (26 ft) and 12 cm (4.7 away from field conditions, the number of viable in) (20). 289 Didymopanax morototoni Table l-Mean annual increment by diameter clas- ses for yagrumo macho (Didymopanax morototoni) measured over a 7-month period within the Luquillo Mountains in Puerto Rico (21) Trees D.b.h.

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