HAYDEN ET AL., PICRODENDRON SYSTEMATICS AND PALYNOLOGY OF PICRODENDRON: FURTHER EVIDENCE FOR RELATIONSHIP WITH THE OLDFIELDIOIDEAE (EUPHORBIACEAE) W. J. HAYDI , W. T. GI.LISt. D. E. STONE, C. R. BROOM1E. \ND G. L. WEBSTER At 11I (c KNOWN to botanical science for 285 years, the genus PicrodendronPlanchon has been poorly understood for most of this time. The most pervasiveproblem has been that of discerning familial relationships, and there have beenadditional difficulties in typifying the generic name (Hayden & Reveal. 1980)and in distinguishing its three nominate species. This paper provides a system-atic treatment for Picroderdron and demonstrates its relationships with Eu-phorbiaceae subfam. Oldfieldioideae Kohler & Webster as evidenced by dataon gross morphology, palynology, anatomy, and cytology. Picrodendron captured the attention of Dr. William T. Gillis while he waspursuing floristic studies of the Bahama Islands. During the decade precedinghis death, Gillis accumulated a considerable amount of information on thisproblematic genus: he was attempting to complete this long-standing projectin the weeks before he died in June, 1979. It has been a privilege temperedwith sadness for one of us (W. .1. H.) to prepare this paper from Gillis's notesand the contributions that he had solicited from the other authors. Herbariumand field studies reported here were performed by Gillis and form the basisfor much of what appears in the generic description and the sections on bio-geography and economic uses: taxonomic judgment at the species level is alsoGillis's. Broome and Stone contributed descriptions of pollen and most of thediscussion concerning the Juglandaceae: information on relationships with theEuphorbiaceae was provided by 'Webster. This paper is a tribute and memorial to Gillis, an indefatigable student ofthe Bahama flora. MATERIALS ANI METHODS Taxonomic treatment of Picrodemnron is based on examination of numerousspecimens in the wild, in cultivation, and in the herbarium. Herbarium spec-imens examined are listed in the AIr NIIx. Pollen descriptions are based upon examination of the following specimens.,lurstrobuxus carunculatus (Baillon) Airy Shaw: New Caledonia, Quinne-Tal.Stauifer & Blanchon 5751 (i)ti ): New Caledonia. Kouebuni. Illrliniann 571(i s). Austrobu.xus eugeniiiolius (Guillaumin) Airy Shaw: New Caledonia, (iuil-i Prcsidcnt and i Cllo s of Harvartd (ollcge. 1,a-4.I:rn ul io ' t/ rn lIld ir'/nor un 65: 11)5-12'. lianuai 1 841984]
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