SystematicBotany (1987), 12(1): pp. 1-8 C Copyright1987 by the American Society of Plant Taxonomists Systematicsof Croizatia (Euphorbiaceae) GRADY L. WEBSTER and LYNN GILLESPIE Botany Department,University of California,Davis, California 95616 JULIAN STEYERMARK Missouri Botanical Garden, St. Louis, Missouri 63166 ABSTRACT.Croizatia, a genus known fromPanama and Venezuela (Euphorbiaceae, Phyllanthoi- deae), has been considered closely related to the Old World genus Actephila.However, the spinose pollen of Croizatiais very differentfrom the semitectatepollen of Actephila,and the two genera appear clearly distinct.The pollen morphology of Croizatiasuggests a possible relationship with the Oldfieldioideae, and it may be the closest extanttaxon to a connectinglink between the subfam- ilies. Three species of Croizatiaare tentativelyrecognized, including a new species, Croizatia pan- amensis; but species delimitationsmust be regarded as provisional. The Euphorbiaceous genus Croizatia(Steyer- ferencesobserved are the much more reduced mark 1952), named for the eminent student of petals of staminateflowers and the twice bifid the systematics of the Euphorbiaceae, Leon style tips of Croizatia.Although there are other Croizat-Chaly(Steyermark 1983), has long been diagnostic characters pointed out by Steyer- regarded as of uncertain affinity.The first mark (1952), such as the enlarged columella of species published, C. neotropica(Steyermark Croizatia,the overall gross resemblance to Ac- 1952), was described froma fruitingspecimen tephilais striking.Indeed, Gentry(1982) has at- collected in the stateof Anzoategui, Venezuela. tributedto Rodriguez an unpublished combi- Later,Steyermark (1978) added a second species, nation under Actephilafor C. neotropicaand C. naiguatensis,from another fruitingspecimen quotes Rodriguez as statingthat Croizatiais in- found on the Cerro Naiguata, DistritoFederal, distinguishable fromActephila. Venezuela. Despite the uncertaintyregarding the gener- Croizat (in Steyermark1952) stated that the ic status of Croizatia,the floral,fruit, and leaf affinitiesof Croizatiawere close to the Old World charactersappear to provide sufficientdistinc- genus Actephila.In 1978, when C. naiguatensis tions to maintain it as separate fromActephila. was described,the flowersof both species were Furthermore,examination of the pollen grains still unknown, and the affinitiesof the genus with scanning electron microscopyshows that thereforeremained problematical.In the most the pollen of Croizatia(figs. 2, 3) is very differ- recent enumeration of Euphorbiaceous genera ent fromthat of Actephilacollinsae Hunter (fig. (Webster1975), Croizatawas omittedbecause of 4). The pollen grains of A. collinsaeare 40-49 its dubious status;but in the synopticarrange- (x = 46) Amin diameter,subprolate, and tricol- ment of tribes of Phyllanthoideae (Webster porate with large, well-definedcolpi; the exine ined.) its placement appeared to be with either is rather finely semitectate-reticulate.These the Wielandieae or Amanoeae. Levin (1984), in charactersagree ratherwell with the light mi- a survey of leaf charactersin the Phyllanthoi- croscopic observations on other species of Ac- deae, reportsa greatersimilarity of Croizatiato tephila:A. excelsa (Punt 1962), A. nitidulaGag- Savia and Blotiathan to Actephila. nep., and A. ovalisGagnep. (Kohler 1965). Both Recentlyin June 1983, our knowledge of the Punt and Kohler have noted the resemblance reproductive morphology of Croizatia im- of the pollen grains of Actephilato those of An- proved dramatically due to the collection of drachne(s.l.). In contrast,the pollen grains of floweringspecimens of C. naiguatensis.The pet- Croizatianaiguatensis are spherical, 46-56 (x = aliferous flowers(fig. 1) resemble those of Ac- 51) Am in diameter, with the colpi greatly tephila,as Croizat had predicted; there is an es- shortened (ca. 10 ,umlong), the lalongate germ pecial similarity to the flowers of the pore well developed (ca. 10 Am broad); the ex- widespread paleotropical species Actephilaex- ine is tectate-perforateand ornamented with celsa (Dalz.) Muell. Arg. The major floral dif- conical,sharply-pointed spines ca. 3-4 Amhigh. This content downloaded from 169.237.8.35 on Mon, 16 Sep 2013 18:53:23 PM All use subject to JSTOR Terms and Conditions 2 SYSTEMATIC BOTANY [Volume 12 15cm 1m $75mm A \ j ~~5mm (~~~~) 2mm \Y 2.5mm-H FIG. 1. Habit and flowersof Croizatianaiguatensis. A. Pistillate branch with fruitsand flowers. B. Part of staminate branch with flowers. C. Staminate flower with one petal enlarged. D. Pistillode. E. Sta- men. F. Pistillate flower with one petal enlarged. G. Gynoecium with disk, petals, and staminode. H. Cross-sectionof ovary. I. Columella and persistentcalyx on fruitingpedicel. This content downloaded from 169.237.8.35 on Mon, 16 Sep 2013 18:53:23 PM All use subject to JSTOR Terms and Conditions 1987] WEBSTER ET AL.: CROIZATIA 3 7 v, FIGS.2-7. Pollen grains of Euphorbiaceae; scales = 10 ,um. 2, 3. Croizatianaiguatensis (Berry et al. 4124, DAV). 4. Actephilacollinsae (Larsen 33631, MO). 5. Tetracoccusdioicus (Carlquist s.n., cult. Rancho Santa Ana Botanic Garden). 6. Podocalyxloranthoides (Williams et al. 18249,DAV). 7. Amanoaguyanensis (Tillett & Tillett 45256,DAV). This content downloaded from 169.237.8.35 on Mon, 16 Sep 2013 18:53:23 PM All use subject to JSTOR Terms and Conditions 4 SYSTEMATIC BOTANY [Volume 12 TABLE 1. Comparison of morphological charactersof Croizatiawith those of Phyllanthoideae and Oldfield- ioideae. Phyllanthoideae Croizatia Oldfieldioideae Phyllatoxy alternate alternate alternate,opposite, or whorled Stipules usually + + +, reduced, or 0 Petals + or 0 + 0 Staminate mostlyextrastaminal extrastaminal mostlyintrastaminal or 0 disk Pollen mostly3-4-colporate, brevicolpor- brevicolporateor pororate, not echinate ate, echinate echinate Ovules anatropous/hemitropous hemitropous anatropous Styles mostlybifid twice bifid mostlysimple Seeds ecarunculate ecarunculate carunculate or ecarunculate Endosperm +/0 0 + This striking differencebetween the pollen (1984b); the pollen is oblate, tricolporatewith grains of Croizatiaand those of Actephilarein- colpi shortbut not greatlyreduced and with a forcesthe impression,based on gross morpho- tectate-regulateexine with supratectal spinu- logical characters,that the two genera are quite lose sculptural elements. Although Securinega distinct. has been traditionallyplaced in the Phyllan- On the other hand, the echinate, tribrevicol- theae, this appears to have been due to the er- porate pollen found in Croizatiais clearly sim- roneous inclusion of species properlyreferable ilar to pollen of Oldfieldioideae as that group to Flueggea(Webster 1984a). The pollen of the was palynologically defined by Kohler (1965) type species S. durissimais quite anomalous and taxonomicallydelimited by Webster(1967). within the tribeand resemblesto a much great- There is a close resemblance between the pol- er extentpollen of membersof the Wielandieae, len of C. naiguatensisand thatof Tetracoccusdioi- such as Discocarpus. The "S. durissima" cus Parry (fig. 5) and Podocalyx loranthoides pollen type might conceivably bear an ances- Klotzsch (fig. 6), which are considered to be tral relationship to typical "Oldfieldioid" pol- two of the more primitivemembers of the Old- len; however, much furtherstudy is needed fieldioideae on the basis of floral and vegeta- concerning the taxonomic position of S. duris- tive characters(Webster ined.). Podocalyxdif- simaand otherWielandieae beforepossible links fersfrom Croizatia in having tetraporatepollen to the Oldfieldioideae can be substantiated. with a tectate-imperforateexine and in its dis- When the charactersof Croizatiaare tabulated tinctlysmaller diameter (ca. 30 A,m),while Tet- in comparison with the Phyllanthoideae and racoccusdiffers in having 4- to 6-colpoidorate Oldfieldioideae (table 1), it clearlyagrees better pollen and a tectate-regulateexine with gem- with the Phyllanthoideae in five characters mae on the ridges. (petals, staminate disk, ovules, styles,and de- Within the Phyllanthoideae, true spines of velopment of endosperm) and with the Old- the "Oldfieldioid" type have heretoforebeen fieldioideae in only one (pollen). However, unrecorded. The pollen grains of some species most of the resemblance to the Phyllanthoi- of Amanoa are irregularlybaculate; the sculp- deae involves the common possession of prim- turalelements are rod-likewith the apex some- itive (plesiomorphic) characters. When only times expanded or tapered (fig. 7). The differ- derived (apomorphic) characters are consid- ent structureof the "spines" in both Croizatia ered, Croizatiahas two in common with Phyl- and Amanoasuggests thatthe resemblance may lanthoideae (hemitropous ovules, exalbumi- be due to convergence and, therefore,not in- nous seeds) and one with Oldfieldioideae dicative of a close phylogenetic relationship. (echinate pollen). Another taxon within the Phyllanthoideae In table 2, the charactersof Croizatiaare con- which has pollen that bears some resemblance trasted with two putatively primitive genera, to pollen of the Oldfieldioideae is Securinega Wielandia and Podocalyx, in the subfamilies durissimnaJ. F. Gmel., illustrated by Webster Phyllanthoideae and Oldfieldioideae. Here the This content downloaded from 169.237.8.35 on Mon, 16 Sep 2013 18:53:23 PM All use subject to JSTOR Terms and Conditions 1987] WEBSTER ET AL.: CROIZATIA 5 TABLE 2. Comparison of morphological charactersof Croizatiawith a primitivegenus of Phyllanthoideae