Wood Anatomy of Lobelioideae (Campanulaceae)
Sherwin Carlquist
Claremont Graduate School and Rancho Santa Ana Botanic Garden, Claremont, California 91711 U.S.A.
ABSTRACT
The tribe Lobelioideae (Campanulaceae) is represented by woody species in certain insular and island-like areas, most notably the Hawaiian Islands, the mountains of East Africa, and the Andes. Because the lobelioids are basically an herbaceous group in which increase in woodiness is a response to uniform, often tropical conditions, they have developed wood of a type unlike that found in basically woody groups of dicotyledons. Vessel element length and diametet are greatest in species of very wet areas. Ray size appears related to the size of plant: taller, wider rays occur in larger shrubs and trees. Scalariform pitting on lateral vessel walls is common in many lobelioids, especially those of a some what succulent nature where mechanical strength seems less important. To explain how long vessel elements, pre dominantly erect ray cells, and presence of scalariform lateral wall pitting of vessels can occur in such a specialized group of dicotyledons, the concept of paedomorphosis (juvenilism, neoteny) is invoked. Data on 56 species (several collections for many of these) are summarized in chart form, and anatomical features are discussed with relation to both taxonomy and ecology.
LOBELIOIDS OFFER A distinctive example of an herba The large Iobelioid genera Centropogon, Burmeistera, ceous group in which woodiness has apparently in and Siphocampylus are mostly Andean in their de creased in tropical insular and island-like areas. Be velopment (Wimmer 1956). At least some species cause lobelioids have small, easily-distributed seeds, of these genera are significantly woody. Other her they have been able to reach remote oceanic islands baceous families show phyletic increase of woodi and continental mountain tops. Although one may ness in the Andes, especially near the equator: Hydro- not regard lobelioids as a characteristically weedy phyllaceae (Wigandia), Polemoniaceae (Cantua), group, they evidently are, for they have been able to Solanaceae (several genera, notably Solatium, Nico evolve rapidly and sensitively in pioneering areas. tians, Cestrum), Asteraceae (many genera, notably The areas in which lobelioids have increased in wood Espeletia, Senecio, Gynoxys). iness have what could be termed an even or moder From the baccate-fruited Cordilleran lobelioids ate climate: cool tropical or subtropical conditions of South America (e.g., Centropogon, Burmeistera, throughout the year. Oceanic islands have climate Pratia), the baccate-fruited Hawaiian genera (Delis- moderated by the maritime environment, so that the sea, Cyanea, Rollandia, Clermontia) have probably growing season is, in fact, the entire year. High been derived. Baccate fruits are excellently suited mountains close to the equator also have a year to long-distance dispersal, especially if they have long temperate climate: while diurnal temperature small seeds. Although one might not expect this, fluctuation is drastic, winter days are virtually the baccate and drupate fruits must be hypothesized as same as summer days. The Hawaiian Islands and the the dispersal type for fully 50 per cent of the immi highlands of East Africa are probably the most fam grants that must be postulated to account for the ous sites of Iobelioid evolution, but by no means origin of the native Hawaiian flora (Carlquist 1967). the only ones that conform to the climatic regime The Hawaiian baccate lobelioids have radiated in a described above. Among insular areas, islands of spectacular fashion. They include large shrubs, small southeastern Polynesia have endemic woody Iobe trees, palmiform rosette trees, and succulent rosette lioid genera: Apetahia (Raiatea) and Sclerotheca plants. Some species have considerable xylem de (Rarotonga, Tahiti. Marquesas, Rapa). The Andes velopment. The largest Hawaiian Iobelioid sample may not often be regarded as an insular area, but I have collected is about 10 inches in diameter they are: as geologically new high mountains in an 2 (Clermontia clermontioides ). An understanding equatorial region, they have acquired floristic ele of the habits of Hawaiian lobelioids is essential to ments to a great degree by long-distance dispersal. comprehension of the patterns of their wood anatomy. For photographs of these plants, the reader can con 1 These studies were aided by grants from the National sult Rock (1919) or Carlquist (1970). Science Foundation: NSFG-23396, GB-4977x, and GB- 14092. The writer expresses appreciation for this as sistance. 2 Authorities for all species studied arc cited in table 1.
BIOTROPICA 1(2): 47-72. 1969 47 Lobelia, the largest of the lobelioid genera with for a single species, Siphocampylus umbellatus. The capsular fruits, is world-wide in distribution (Wim- survey of anatomy of lobelioids by Ydrac (1905) mer 1956). Very small seed size has undoubtedly describes the primary vascular cylinder, but does not aided this distribution pattern. Some of the Hawai include secondary xylem. One might have thought ian species of Lobelia are rosette plants with appre that at least one species of lobelioid might have been ciable wood development. The East African species included in Brown's (1922) survey of wood anatomy of Lobelia are justly famous. Of these, the alpine of Hawaiian trees, but he did not study any. Wim species are most frequently illustrated. These, al mer's (1956) review of anatomical literature on though large-leaved conspicuous plants, are not as lobelioids reveals a lacuna with respect to wood large or woody as the species of subalpine wet for anatomy, and none of the taxonomic papers by Rock, est, such as L. gibberoa or L. lanuriensis. For illu Hauman, or Hedberg cited above deals with ana strations of African Lobelia species and information tomical aspects. regarding their taxonomy and ecology, the reader can consult Hauman (1933) and Hedberg (1957, 1964). MATERIALS, METHODS, AND Lobelia has reached the Hawaiian Islands—per ACKNOWLEDGMENTS haps through more than one colonization. The bog species, L. gaudichaudii, would represent one of these The collecting of wood samples contributing to this hypothetical colonizations. The blue-flowered spe study began in the Hawaiian Islands in 1953, and cies, such as L. hypoleuca, would represent a second was continued during subsequent field work in the colonization. The endemic Hawaiian genus Trema- Hawaiian Islands, southeastern Polynesia, and East tolobelia may represent a third colonization by Lo Africa. Many individuals have aided my field work belia, of which Trematolobelia is, in essence, a seg or contributed wood samples. I am particularly in regate. Likewise, Apetahia and Sderotheca seem to debted to Dr. George W. Gillett, Dr. Olov Hedberg, me to be colonizations of southeastern Polynesia by and Dr. William L. Stern in this regard. However, Lobelia-like ancestors. I believe that Apetahia and many others have been of substantial and indispens Sderotheca are closely related, although Wimmer's able assistance to me with respect to field work, or (1953) treatment suggests no close relationship be microtechnical tasks relating to this paper. I take tween the two. Brighamia, which Wimmer places pleasure in acknowledging the help of the follow next to Apetahia, has a papery, rather than a woody ing individuals: Miss Jane Benjamin, Mr. Edwin capsule. The relationships of Brighamia are not ob Bonsey, Mr. Norman Carlson, Prof. Lincoln Con vious at present, but they might lie with Isotoma stance, Mr. Carl Corte, Mr. Ralph Daehler, Dr. Al rather than the baccate genera or with Lobelia. fred G. Diboll, Mr. Libert Landgraf, Mr. James Lar son, Dr. Elizabeth McClintock, Mr. Timothy O. Mc- In a group such as Lobelioideae, the interest in Gee, Miss Ann Piatt, Mr. Charles F. Quibell, Mr. E. S. herent in the study of wood anatomy lies in how Reckard, Dr. Harold St. John, Mr. Herbert Shipman. patterns of wood anatomy in an essentially herba Prof. A. C. Smith, the late Miss Ella Stephens, Dr. ceous family differ from those in a woody family. Benjamin C. Stone, Dr. Frank Tabrah, Miss Linda The wood of lobelioids is, in fact, different from Thorne, Prof. Robert F. Thorne, Mr. Bunichi Usa- that of a typically woody family. Examples from gawa, and Prof. Warren H. Wagner, Jr. My 1953 lobelioid woods were cited in a paper dealing with field work in the Hawaiian Islands was aided by juvenilism (Carlquist 1962) for this reason. The funds from Mr. and Mrs. R. M. Bauer. nature of these distinctive features and how they re late to ecology and evolution are detailed in the dis A few wood samples were derived from her cussion section that terminates this paper. barium specimens, but the vast majority were col Few studies have been done on wood anatomy lected in the field, and are documented by herbarium of herbaceous dicotyledons. This is especially true specimens collected at the same time. All specimens of lobelioids. The summary for the family given investigated in this study are listed in table 1. by Metcalfe and Chalk (1950), for example, is based Lobelioid woods are very soft and subject to mold only on the description by Record and Hess (1943) infestation. This could be effectively countered only
FIGURES 1-4. Figures I, 2. Apetahia raiateensis H. Baill., Carlquist 666. Figure 1. Transection; note vessel group ings.—Figure 2. Tangential section. Course of rays and fascicular areas is wavy. Figures 3, 4. Brighamia insignis A. Gray, Carlquist 1649. Sections from more fibrous wood near base of stem. Figure 3. Transection. More fibrous portions of fascicular areas above.—Figure 4. Tangential section. More fibrous portions of fascicular areas at left. Magnification for figures 1—4 (and also all other figures except figures 41—46) indicated by micrometer scale at top of figure 1, photographed at same scale as wood sections. Micrometer scale shows 1.5 mm.
48 Carlquist Wood Anatomy of Lobelioideae 49 by several precautions. Bark was removed, wood dii Rock are variously juvenile stages of C. tritoman- samples were air-dried under shelter as well as pos tha A. Gray, according to my field observations (Carl- sible in the time available, then shipped to Clare- quist 1970). Rollandia pinnatifida G. Don appears mont, California, where the dry climate permitted to be the correct name for plants much better known successful drying. During shipment molding did as Rollandia kaalae Wawra, and Cyanea selachicauda not occur because wood samples were dusted with Degener. Clermontia loyana Rock, C. rockiana E. paraformaldehyde powder before they were sent. Wimmer, and C. caerulea var. greenwelliana E. Wim Liquid-preserved wood samples were prepared for mer, are minor variants or synonyms which probably some lobelioids: Brighamia insignis. Lobelia gibberoa can be regarded as C. caerulea (Gaudich.) Heller. (sample prepared at Strybing Arboretum, San Fran Clermontia kohalae var. robusta Rock is merely typi cisco, by Dr. Elizabeth McClintock), and L. tortuosa. cal C. kohalae Rock in which short internodcs pre These were important, for living cells comprise much dominate because of advanced age of a plant. Cler of the wood in lobelioids. The wood sample of montia ivaimeae Rock is probably a hybrid between Brighamia insignis figured earlier by the writer C. parvijlora Gaudich. and C. kohalae Rock, and C. (1962) is from the succulent wood typical of most leptoclada Rock may be a hybrid between C. kohalae of the stem. The wood figured in the present paper and C. drepanomorpha Rock. Clermontia drepano- (figs. 3, 4) was taken from a more fibrous, denser morpha can be regarded merely as a bog subspecies portion of the stem near the base of a plant. of C. kohalae. When careful taxonomic studies in corporating field studies are undertaken by future Wood sections and macerations were prepared workers, other species of Hawaiian lobelioids now according to the usual techniques. Qualitative and recognized may have to be reduced to synonymy. quantitative features incorporated into table 1 are those which seemed to show significant differences The discovery of patterns of juvenilism, or paedo- within the Lobelioideae. Most are self-explanatory. morphosis, in wood of lobelioids (Carlquist 1962) Libriform fiber width refers to measurements made suggested that investigation of different portions of across the widest portion of a fiber, as seen in macer a single plant would be appropriate. Such analyses ation, rather than toward one of its tips, and the are shown for wood samples from several species result of averaging the widest diameter of fibers is in table 1, and represent selections of particular expressed in the table. Pit diameter refers to dia growth forms: large freely-branched shrubs or small meter of circular pits or the shorter diameter of ellip trees {Clermontia arborescens, C. hawaiiensis, C. tical or elongate pits. With few exceptions, 50 kakena, and C. montis-loa), a large palmiform rosette measurements or more provided the basis for aver tree (Cyanea leptostegia), and a small rosette plant ages in all measurements in which averages are ex (Cyanea marksii). Plants with only limited sec pressed. ondary xylem accumulation were not, in general, Most of the lobelioid wood samples studied here analyzed with respect to different portions because were collected in the Hawaiian Islands. A relatively differences would not be as well demonstrated by intensive coverage of species was attempted because them. In the case of Cyanea carlsonii, the excessive of the rarity of these plants; the writer presumed rarity of this species dictated that the main trunk that many plants similar in habit might have similar of a plant could not be cut, and a sample was taken wood anatomy. Wood samples of Hawaiian lobeli from a lateral root. oids have been subdivided and exchanged with lead ing wood collections, such as that of the U.S. Nation ANATOMICAL COMPARISONS al Museum. Many replicate slides of wood sections were prepared, and these are also available for ex VESSEL ELEMENTS.—The vessel elements of most change from the author. lobelioids are exceptionally long for a group of her Some of the Hawaiian species which appear to baceous plants, a group considered highly specialized have been omitted from the present study are, in my according to most tenets of angiosperm phylogeny. opinion, synonyms. For example, Cyanea bryanii In fact, the vessel elements of lobelioids are fairly Rock, C. nolimetangere Rock, C. rollandioides Rock, long in relation to dicotyledons as a whole. The C. submuricata E. Wimmer, and probably C. fernal- vessel element length distribution graph of Metcalfe
FIGURES 5-8. Figures 5, 6. Clermontia clermontioides (Gaudich.) Heller var. clermontioides, Carlquist 1667. Figure 5. Transection, showing growth rings.—Figure 6. Tangential section. Note very tall rays, relatively wide fascicular areas. Figures 7, 8. Clermontia clermontioides var. singuliflora (Rock) Hochr., Carlquist 1760. Figure 7. Transec tion. Vessels are relatively wide, prominently grouped.—Figure 8. Tangential section. Wide, relatively short rays and narrow fascicular areas with short fibers are shown. Scale of magnification shown in figure 1.
50 Carlquist Wood Anatomy of Lobelioideae 51 52 Carlquist and Chalk (1950) shows that most dicotyledons have so that the most recently formed elements are short vessel elements averaging between 200 and 600 mic er. (E.g., compare wood from a small stem of Cler rons in length. As the lengths shown here in table montia clermontioides, fig. 6, with recent wood from 1 indicate, a surprising number of lobelioids have an old stem of that species, fig. 8.) This confirms vessel elements averaging more than 500 microns. the pattern claimed earlier (Carlquist 1962) for Unfortunately, no figures for vessel element length wood in certain herbaceous species (although this in herbaceous dicotyledons as a whole are available. tendency is not without exception in herbaceous Our figures for dicotyledons at large are, of course, plants). based on truly woody dicotyledons (that is to say, Comparison within a single plant between length mostly trees) almost exclusively. The average vessel of vessel elements in an upper branch and length of element length for Asteraceae as a whole (353 col vessel elements near the pith at the base of the plant lections of 328 taxa) was 235 microns (Cariquisr yields somewhat contradictory figures. Figures for 1966). Cyanea leptostegia would suggest that longer vessel The longest average vessel element lengths were elements occur in upper portions of a plant (fig. observed in Lobelia gibberoa (fig. 22), L. lanuriensis 26). However, little difference or even the reverse (fig. 24), and Trematolobelia macrostachys ( fig. 40). is suggested by other lobelioids. More analyses would The two species of Lobelia are African, and are not be desirable to demonstrate trends within a single from the alpine zone, but from the very wet sub- plant. alpine forest zones. "Trematolobelia macrostachys Vessel diameter shows an appreciable range in is also a wet forest plant; it occurs only in the wet the lobelioids studied, but this range does not appear test forest areas of the Hawaiian Islands and in bog related to ecology of the various species. Instead, areas adjacent to wet forest. there appears to be a relationship between size of There is not a perfect correlation between wer plant and vessel diameter. The species which be habitat and long vessel elements, but the relationship come the largest plants have the widest vessels (figs. is close. For example, of the species of Rollandia, R. 5, 7, 21, 25, 27, 35). The narrowest vessels occur humboldtiana (fig. 26) occupies the wettest sites: in Brighamia and Lobelia, which have the smallest deep shady gulches in rain forest. Most lobelioids plant size (see figs. 1, 3, 11, 17, 19 especially). can, to be sure, be said to be mesic in preference. However, in a given plant which ultimately reaches However, Lobelia telekii. with the shortest average a large size, vessels in a young plant appear to be vessel element length of lobelioids studied here, oc just as large, approximately, as those in an old one. cupies the most xeric locality: the dry alpine zone, Grouping of vessels appears to be a significant about 14,000-15,000 feet elevation, on Mt. Kenya. feature in various dicotyledonous families, but in Other species with short vessel elements are also lobelioids the extremes are not wide nor do they xerophytes. Lobelia bambuseti and L. keniensis also appear to be consistently related to particular factors. belong to the Afroalpine flora. Brighamia insignis There is a relatively great degree of vessel grouping (fig. 4) occurs on dry lowland cliffs of the Hawaiian in Lobelia gaudichaudii var. gloria-montis (fig. 13) Islands. Lobelia tortuosa (fig. 20) is native to in and Clermontia persicaefolia (fig. 9). Most lobeli termittently wet cliffs of low or medium elevations oids show small groupings of vessels, with many in the Hawaiian Islands. Presence of long vessel ele vessels solitary (figs. 3, 5, 11, 17, 19, 21, 23, 25, 27, ments in mesophytic species, shorter ones in xero- 29, 33, 37, 39). Pore clusters characterize a few phytic ones is to be expected if the considerations lobelioids (figs. 1, 7, 13), but pores in radial multi derived from study of Asteraceae (Carlquist 1966) ples is the characteristic arrangement of most lobeli apply to Lobelioideae as well. Length of vessel ele oids (figs. 1,9, 15, 21, 27, 35). ments also appears to bear some correlation with size Pitting in vessel walls of lobelioids frequently of plants. Tall rosette trees and larger shrubby spe includes elliptical or elongate pits, sometimes so cies often seem to have longer vessel elements. characteristically that a scalariform pitting pattern Study of ontogenetic change in length of vessel can be said to be present. Such pits have been re elements in lobelioids indicates a remarkably uniform ported for the genera Pratia, Lobelia, and Centro- trend. There is a steady decrease in length with age, pogon by Metcalfe and Chalk (1950) and for Brig-
FIGURES 9—12. Figures 9, 10. Clermontia persicaefolia Gaudich., Carlquist 1754' Figure 9- Transection, showing wide rays, vessels in radial multiples.—Figure 10. Tangential section. Fascicular areas are undulating in course, vessel elements and fibers relatively short. Figures 11, 12. Delissea undulata Gaudich., Carlquist 2250. Figure 11. Tran section. Vessels are rather narrow.—Figure 12. Tangential section; rays are narrow and rather tall. Scale of magni fication shown in figure 1.
Wood Anatomy of Lobelioideae 53 harma insignis and Delissea undulata by the writer (fig. 46), seem to represent simple plates or simply (1962). As indicated in table 1, elliptical pits are plates partly or wholly subdivided by one or more frequent in particular lobelioids. They are present bars. The bars are, however, irregular in shape and to a lesser extent in virtually all of the remainder orientation. Sometimes double perforation plates, of lobelioids. Delissea (fig. 44), Rollandia, and each circular and separated from the other of the Brigbamia are especially rich in elongate vascular pair by a wide bar, occur on lobelioid vessels, as in pits, but individual species in the other genera are Cyanea leptostegia. Perforation plates deviating equally striking in this regard, as in Lobelia tortuosa slightly or markedly from simple are in a minority or Cyanea tritomantha (fig. 43). The rather suc in the wood of any lobelioid species, but at least a culent rosette tree, such as Lobelia gaudichaudii, De few were observed in virtually all of the species lissea undulata, or Cyanea aculeatiflora, is the growth studied here. They were particularly conspicuous form in which scalariform-Iike pitting occurs most in Lobelia and its close allies, especially Lobelia gib- commonly. A discussion of the possible significance beroa, L. neriifolia, and Trematolobelia macrostachys. of this pitting in woody herbs was given earlier by Such perforation plates probably do not represent the writer (1962) and is analyzed further in the dis indicators of primitiveness for lobelioid woods, which cussion section below. are so notably specialized in other respects (for ex Although no helical thickenings ("tertiary thick ample, no tracheids are present in lobelioid woods). enings") are present in secondary xylem vessels of Rather, these malformed perforation plates may rep lobelioids, there are grooves in vessel walls. These resent juvenilisms, as they evidently do in Asteraceae. grooves interconnect pit apertures, and can be seen In that family, malformed perforation plates were most clearly where portions of a vessel wall are most common in a genus of insular rosette trees with shaved away obliquely by the sectioning process. relatively little secondary xylem, Dendroseris (Carl- Such grooves are shown for Delissea undulata in fig. quist I960). 45. They were also observed in Cyanea leptostegia. LIBRIFORM FIBERS.—The length of libriform fib Presence of grooves might be related to a modest ers parallels that of vessel elements. Most of the spe degree of xeromorphy: both Delissea undulata and cies with notably long libriform fibers have large Cyanea leptostegia are species of the relatively dry plant size: Cyanea angustifolia, C. coriacea, C. lep koa (Acacia koa A. Gray) forests. tostegia, C. tritomantha, Clermontia arborescens, C. Perforation plates of lobelioid vessel elements hawaiiensis, C. kakeana, and Rollandia pinnatifida. are basically simple, with wide conspicuous borders. A correlation between size and mechanical strength Perforation plates termed "scalariform" were reported seems evident. If true, thicker-walled fibers also by Metcalfe and Chalk (1950) for "Lobelia gibberoa ought to be present in species with greater plant and possibly a few other species of Lobelia!' The size. The tallest of the lobelioids, Cyanea leptostegia, perforation plates indicated by this remark have does indeed have thick-walled fibers (fig. 42), es been observed in various lobelioids by the writer. pecially in upper portions of the plant. Basal por I do not believe that they can be termed scalariform tions have a few bands of thin-walled fibers also in the ordinary sense. Lobelioid perforation plates, (fig. 41). Prominent bands of thin-walled and as illustrated here for Trematolobelia macrostachys thick-walled fibers were observed in Lobelia tor-
FIGURES 13-16. Figures 13, 14. Lobelia gaudichaudii DC. var. gloria-montis (Rock) St. John, Carlquist 553. Fig ure 13. Transection.—Figure 14. Tangential section. Wider rays are relatively unaltered from primary ray condition. Figures 15, 16. Lobelia gaudichaudii var. kauaensis A. Gray, Stem & Carlquist 1331- Figure 15. Transection.—Figure \6. Tangential section. Rays are relatively narrow; a few uniseriate rays may be seen. Scale of magnification shown in figure 1.
FIGURES 17-20. Figures 17, 18. Lobelia neriifolia A. Gray, Carlquist 1931. Figure 17. Transection. Fibers are notably thin-walled.—Figure 18. Tangential section. Figures 19, 20. Lobelia tortuosa Heller, Carlquist 1658. Figure 19. Transection. Growth rings are prominently shown.—Figure 20. Tangential section. Note short vessel elements. Scale of magnification shown in figure 1.
FIGURES 21-24. African species of Lobelia. Figures 21,22. Lobelia gibberoa Hemsl., Carlquist 2829. Figure 21. Transection. Little or no growth ring formation is present.—Figure 22. Tangential section. Rays are narrow in com parison to fascicular areas. Figures 23, 24. Lobelia lanunensis de Wild., Hedberg 353- Figure 23. Transection, show ing abundance of vessels.—Figure 24. Tangential section. Scale of magnification shown in figure 1.
54 Carlquist Wood Anatomy of Lobelioideae 55 56 Carlquist Wood Anatomy of Lobelioideae 57 58 Carlquist tuosa (fig. 19). vessel group. Axial parenchyma cells are not easy to Both Lobelia tortuosa and Brigbamia insignis differentiate from erect ray cells when seen in a longi have libriform fibers with very thin walls. Some tudinal section. They can be identified by their of these are blunt-tipped and non-lignified and there usual appearance as strands of two cells. Strands of fore might be termed axial parenchyma. If these were three or four cells were observed in Cyanea lepto- to be termed axial parenchyma, one might expect stt %ia, them to occur as strands of two, for strands of two Rays in lobelioids are almost all multiseriate. In cells do occur when true axial parenchyma is present no specimens were uniseriate rays of more than mini in most lobelioid species. mal frequency. Where multiseriate rays are large Most lobelioids could be said to have relatively and numerous, as is the case in lobelioids, uniseriate wide thin-walled libriform fibers. Notably narrow rays can be expected to be infrequent. Where multi- fibers characterize species of Delissea (fig. 11) and seriate rays are extensive and isolated from other Lobelia (figs. 13, 15, 17, 19, 21, 23), whereas wide such rays only by narrow fascicular areas (e.g., figs. fibers are seen in some species of Clermontia (fig. 2, 4, 8, 10), most groups of cells that approach being 7) and Cyanea (fig. 27). Most lobelioid woods uniseriate rays would very likely be attached to one seem, by virtue of moderate fiber-wall thickness, to of the adjacent multiseriate rays, and therefore they have limited mechanical strength. This impression is could not qualify as uniseriate rays. reinforced by the fact that walls of libriform fibers Very tall rays characterize lobelioids. Even in some species show shrinkage patterns suggesting though the areas of tangential sections studied were that they could be called gelatinous fibers. Fibers relatively large, many rays in sections of some spe in Apetabia raiateensis, Cyanea tritomantba, and C. cies could not be measured because only portions of marksii can give this appearance. them were included within the section. Such species The three taxa for which liquid-preserved sam are reported in table 1 as "more than 5 mm" or ples were available {Brigbamia insignis, Lobelia gib- "more than 10 mm" tall, depending on the height beroa, L. tortuosa) have nuclei in mature libriform of rays measurable and the proportion of rays that fibers. These fibers are, in respects other than the exceeded the length of the tangential section. Such ocairrence of nuclei, typical libriform fibers. These very tall ray height characterizes Brigbamia insignis might be called "nucleated fibers." If so, that term (fig. 4), Clermontia clermontioides (figs. 6, 8), is not appropriate for the bands of short cells, be Lobelia gaudicbaudii (figs. 14, 16), Cyanea lepto lieved to be the product of fiber dimorphism (Carl stegia (fig. 26), C. tritomantba (fig. 28), C. grim- quist 1961) in such genera as Erytbrina and other esiana (fig. 30), C. recta (fig. 32) and the species legume genera (Cumbie I960) or Dubautia (Carl- of Rollandia (figs. 34, 36). Relatively short rays, quist 1958). All species of lobelioids studied have on the contrary, characterize Apetabia raiateensis septate fibers. In any given sample, all fibers are (fig. 2), Clermontia persicaefolia (fig. 10), Lobelia not septate, but an appreciable or even large pro keniensis, L. neriifolia (fig. 18), L. seguinii. L. tor portion of them are. The presence both of nuclei tuosa (fig. 20), and Sclerotheca margaretae (fig. 38). and, often, septa, suggests fibers to be rather paren There are various possible correlations between ray chyma-like, especially in the case of bands of thin- dimensions and growth forms or ecological factors. walled fibers. If so, this might be regarded as re Such correlations probably are significant on the level lated to the paucity of axial parenchyma cells in of individual species. For example, large rays in lobelioid woods. Brigbamia may be related to the stem succulence and PARENCHYMA.—Axial parenchyma was reported juvenilism of that plant. Short rays in Clermontia by Record and Hess (1943) for Siphocampylus as persicaefolia may reflect the stunted shrubby habit scanty vasicentric. This holds for all the lobelioids of that species. Short rays in the Afroalpine lobelias studied, although some, such as Trematolobelia macro- —L. keniensis and L. telekii—may be correlated with stacbys (figs. 39,40), have very few axial parenchyma alpine types of xeromorphy and with the very short cells. Others, such as Cyanea leptostegia (fig. 42, up length of vessel elements. Tall rays may reflect the per left) have more numerous cells, although not succulent rosette-tree habit in certain species of Cy enough to form an unbroken sheath around a vessel or anea, Lobelia (L. gaudicbaudii), and Rollandia.
FIGURES 25-28. Rosette-tree species of Cyanea. Figures 25, 26. Cyanea leptostegia A. Gray, Carlquist 1795. upper portion of plant. Figure 25. Transection.—Figure 26. Tangential section. Rays are notably tall, vessel elements long. Figures 27, 28. Cyanea tritomantba A. Gray, Carlquist 2245 (adult plant, wood from near base). Figure 27. Transec tion. Note rather wide vessels.—Figure 28. Tangential section. Rays are large, composed of rather large cells. Scale of magnification shown in figure 1.
Wood Anatomy of Lobelioideae 59 Exceptionally wide multiseriate rays (measured oids. However, only one of the species studied has as number of cells wide at the widest point) char ray laticifers: Lobelia tortuosa (figs. 19, 20). acterize Apetabia raiateensis (fig. 2), Brighamia GROWTH RINGS.—Growth rings occur as bands of insignis (fig. A), Clermontia arborescens, C. cler- exceptionally thin-walled parenchyma-like fiber or montioides var. singuliflora (fig. 8), C. persicaefolia fibriform parenchyma cells, as mentioned above. Be (fig. 10), Lobelia gaudichaudii var. gloria-month cause woody lobelioids occur in relatively uniform (fig. 14), L. tortuosa (fig. 20), Cyanea recta (fig. climates, one might expect inconspicuous growth 28), C. grimesiana (fig. 30) and the species of Rol rings. This is, in fact, the case. Growth rings seem landia (figs. 34, 36). Relatively wide rays are also to be formed with relation to wet and dry seasons. usually rather tall, as in Rollandia. The commonness The dry seasons are accompanied by thin-walled fib within lobelioids of tall, wide rays seems related to ers, apparently. the basically herbaceous nature of the family. Cer Examples of growth rings may be seen here for tainly, breakup of large multiseriate rays which cor Brighamia insignis (fig. 3), Clermontia clermonti- respond to primary rays can often be seen in sec oides (fig. 5), Lobelia neriifolia (fig. 19), Cyanea tions. recta (fig. 31), Rollandia angustifolia (fig. 33; rings Ray histology in which ray cells are most com very vague), and Sclerotheca arborea (fig. 37). The monly erect, with a few square cells and very few or contrast between the two types of fibers within a no procumbent cells, characterizes most Iobelioid single stem is shown at higher magnification for woods. This ray type, not mentioned by Kribs Cyanea leptostegia (figs. 41, 42). (1935) in his survey of ray evolution, was incorpo LATEX DEPOSITS.—Deposits of latex were seen in rated into a phylogenetic scheme by the writer several of the woods, for example, in vessels of Rol (1961). However, the explanation of this ray type landia angustifolia (fig. 33). I suspect that such seems best related to juvenilism, as suggested in a deposits are artifacts, produced by entry of latex subsequent paper (Carlquist 1962). Of the lobeli into vessels when the wood sample was cut. When oids studied here, very few have any appreciable one takes a wood sample from a living Iobelioid numbers of procumbent cells in rays. Species which plant, drops of latex often are smeared over cut wood do have them include Lobelia gaudichaudii (fig. surfaces. There are, with the exception of Lobelia 14), L. keniensis, L. neriifolia (fig. 18), L. telekii, tortuosa, no laticifers observed in Iobelioid woods and L. tortuosa (fig. 20). These species all have that would release latex deposits into intact living relatively short vessel elements also, so that they may stems. be said to have shorter cambial initials, both fusi No crystals were observed in Iobelioid woods. form and ray. In dicotyledons at large, rays composed predom DISCUSSION inantly of erect cells seem very similar to rays with Several collections, often comparable with respect erect cells exclusively, that is to say, a rayless condi to size and age of wood sample, were used for study tion (because the erect cells are equivalent to libri- of a number of Iobelioid species. Some of these, form fibers and may be termed such). Rayless woods for a given species, show close agreement; others seem to occur in basically herbaceous groups. One differ strongly in quantitative measures. Different might expect from considerations such as these that degrees of juvenilism or adulthood might account a rayless condition might occur in lobelioides. In fact, for some differences, differences in sampling for Centropogon tessmannii is virtually rayless. others; but those botanists having experience with Ray cells of most lobelioids have thin lignified quantitative measurements in wood anatomy realize walls. The only notable exception is Brighamia that quantitative data must be critically interpreted. (figs. 3, 4), in which walls are nonlignified. In A high degree of consistency in results is a prerequi conspicuous pits characterize ray cells of lobelioids. site for interpretations. With this in mind, the Lobelia telekii. however, has conspicuous, rather large following comments can be offered. pits. One might have expected that laticifers, which During the ontogeny of a stem in a typical are abundant in Iobelioid stems (Metcalfe and Chalk woody dicotyledon, transverse subdivision in fusi 1950, Ydrac 1905) would extend into rays of lobeli form ray and cambial initials ordinarily occurs at
FIGURES 29-32. Figures 29, 30. Cyanea grimesiana Gaudich., Carlquist 2160. Figure 29- Transection. Growth ring visible just above center.—Figure 30. Tangential section. Rays are notably wide, tall. Figures 31, 32. Cyanea recta (Wawra) Hillebr., Carlquist 1990. Figure 31- Transection. Vague growth rings evident.—Figure 32. Tangen tial section. Some groups of fibers suggest storying, but a truly storied condition is not present. Scale of magnification shown in figure 1.
60 Carlquist Wood Anatomy of Lobelioideae 61 62 Carlquist the close of primary growth, so that shorter cambial cause only as elongation ceases can more rigid ele initials are ordinarily achieved at this point. In many ments be formed. If the ideas just described are herbaceous dicotyledons, however, subdivision of correct, selection for mechanical strength in a species cambial initials proceeds very slowly. Consequently, would minimize anything but circular bordered pits these plants can have longer vessel elements and directly after production of secondary xylem by a libriform fibers and more numerous erect ray cells newly-initiated cambium. Types of pitting, such as than one would expect on the basis of the woody scalariform, which feature broad areas of pit mem dicotyledon pattern (Carlquist 1962). These her branes, would be ideal for translocation until or un baceous patterns are clearly illustrated by lobelioids. less selection for mechanical strength predominated Therefore, long vessel elements in lobelioids need over the value of broader pit areas. In this case, a not be considered as a retention of a primitive con lobelioid with maximized selection for strength dition per se, but rather a retention of a juvenile would be expected to have only circular bordered condition. Thus, longer vessel elements can be pits on vessels. This does appear to be true. Cyanea achieved by a change in ontogeny, and one need not leptostegia, which has libriform fibers with notably postulate that evolution inevitably and invariably re thick walls, suggesting strength, has circular bordered sults in shortening of vessel elements. Production pits exclusively. Prominent scalariform pitting in of longer vessel elements would not be as likely species such as Brighamia insignis and Lobelia tor- under xeric conditions as under mesic ones. A high tuosa may well be correlated with minimal mechani proportion of erect ray cells would be expected to cal strength in these species with small plant size. be correlated with longer vessel elements in her Data on lobelioid woods suggest, as a generality, baceous dicotyledons such as lobelioids. The fact that shorter, wider rays are related to plants of that procumbent cells are relatively abundant in smaller size and with less mechanical strength; taller, Lobelia telekii and other lobelioids with short vessel wider rays occur in large shrubs, small trees, and elements and libriform fibers is a demonstration rosette trees typically. Interestingly, wider vessels are of this principle. apparently also correlated with larger plant size. In The occurrence of scalariform or transitional the genus Lobelia, the wider vessels may be found in (mixed elongate, elliptical, and circular) pitting in L. gibberoa and L. gaudichaudii var. kauaensis. which vessel walls in so many of the lobelioids can be re are the largest lobelias utilized in the present study. garded as a form of juvenilism (Carlquist 1962). The correlations cited above suggest that habit These pitting characteristics in an herbaceous group and ecology are prime determinants with respect to can be viewed in another perspective, however. The wood anatomy. Although one can describe distinc lack of mechanical strength of lobelioid woods has tions among genera and species strictly as taxonomic been mentioned above. Are broader, longer pits matters, ultimately the factors underlying these dif present when there is no strong selection for me ferences should be sought. Lobelioids appear to be chanical strength, and when there is a retention of a good group for demonstration of these correlations, this pattern from the primary xylem? Primary although the data of the present study are only an xylem is usually minimal in mechanical strength be approximation toward this goal.
FIGURES 33-36. Wood sections of Rollandia. Figures 33, 34. Rollandia angustifolia (Hillebr.) Rock. Carlquist 1750. Figure 33. Transection. Dark spots are latex deposits in vessels.—Figure 34. Tangential section. Rays are tall, wide. Figures 35, 36. Rollandia humboldtiana Gaudich., Carlquist 1630. Figure 35. Transection. Vessels are relatively wide.—Figure 36. Tangential section. Scale of magnification shown in figure I.
FIGURES 37-40. Figure 37. Sclerotheca arborea (Forst.) A. DC, M. L. Grant 4214. Transection. A zone of thin- walled fibers visible in center.—Figure 38. Sclerotheca margaretae F. Brown, St. John 15586. Tangential section. Erect ray cells simulate the short fibers. Figures 39, 40. Trematolobelia macrostachys Zalhbr. var. kauaiensis Rock. Carlquist 1785. Figure 39- Transection. Rays are difficult to differentiate from fascicular areas in this view.—Figure 40. Tangential section. Note long vessel elements, prominence of erect cells in rays. Scale of magnification shown in figure 1.
FIGURES 41-46. Figures 41, 42. Cyanea leptostegia A. Gray, Carlquist 1795, transections. Figure 41. Thin-walled fibers from growth ring of wood sample taken near base of plant.—Figure 42. Thick-walled fibers of sample taken from upper portion of plant. Figure 43. Cyanea tritomantha A. Gray, Carlquist 2245. Vessel, showing scalariform pit ting, from tangential section. Figures 44, 45. Delissea undulata Gaudich., Carlquist 2250. portions of tangential sec tion. Figure 44. Vessel wall, showing near-scalariform condition of pitting.—Figure 45. Vessel wall, showing grooved or striate condition of wall. Part of wall, below, is shaved away by sectioning.—Figure 46. Tremato/obelia macro stachys Zalhbr. var. kauaiensis Rock, Carlquist 1783, portion of radial section showing several perforation plates in dicating several anomalies. Figures 41—46, scale of magnification shown by portion of photograph of micrometer below figure 43. Lines of micrometer = 10 micron rulings.
Wood Anatomy of Lobelioideae 63
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E E £ 8W :< u 1 i-* esse l Itiser i ibrif o leter . 2 1- M JB ss w 1 - li a / * B walls . 3 librif c 3 a& pit s E £__ *9 I dea l ie r pe r gr c P. i librifo n C u 2J elemen i yj « = | 1 s •%u -i. _ a U elli p •2 * "8 average , Widt h Lengt h Diam e Vesse l 53 ' J Vessel s Diame i Wides t Vesse l H NAME Vesse l Longes t vesse l ( OLLBCnON Vesse l diamet e Vessel s Wides t vessel , Diamete r vess e o \S Lengt h Diamete r Thicknes s X > 12. 60 88 v9 9 E 694 3 2 5 2.1 Clermnntia peleana Rock Carlquist 611 (RSA) 412 564 128 •j 728 3 1 5 3.4 9.1 96 1.6 E S29 $7 6 3,i 8.9 -i 96 3.1 10 i-: Clermonlia persicaefolia Gaudich. Carlquist 1754 (RSA) 15.5 423 663 68 84 5.1 1 1 C 950 J 8 - 2.7 1 1 3 6 s 1.3 7 E 440 .33 2 > 10 Cyanea aculeatijlora Rock Carlquist 5" I (RSA I r 401 650 84 120 1.9 12 E 883 38 -i > 10 11.1 Carlquist 2131 (RSA) -si J..' - C 662 28 •I 2.2 2.9 568 69 107 1.8 10 1 906 14 5 >10 6.5 5 5 SS ii Cyanea acuminata (Gaudich.) Hillebr. Carlquist 576 (RSA) 510 '31 50 L.6 •i C 712 24 3 76 1.4 in C 881 J 3 4 >5 10.8 58 117 Carlquist 220" (RSA) 539 706 60 95 1.7 6 -65 27 5 3-5 6.2 11.2 Cyanea angustifo/ia (Cham.) Hillebr. c s-i 114 1.7 8 E 883 ,0 6 4.7 var. angustifolia - 93 130 2.7 7 E S12 3 3 6 >5 9.1 Carlquist H-5 (UC) 677 893 56 88 3.1 c 819 $3 5 >5 ".1 908 3 4 2.1 5.1 Carlquist 1621 (RSA) 559 824 67 100 109 177 2.0 9 E 2.8 1 i 1009 3-1 5 3.3 8. • v.ir. lameiitella Hillebr. c 2.6 8 !•: 877 3 3 4 2.2 i I 6 Carlquist 1725 (RSA) 581 887 68 92 2.8 1 ! 819 122 225 3^ 5 2.3 9.8 6 •1.5 Cyanea asplenifolia (Mann) Hillebr. Forbes 2540 (B1SH) - c 9i 147 1.8 s E 940 )8 2.5 423 757 64 99 2.5 E 692 •1 6 2.8 i 1 6 3.9 15 i Hillebr. Carlquist 561 (RSA; 469 658 70 7 84 118 2.6 9 [•: 672 31 99 2.1 1 722 10 5 5 3 11.3 Carlquist 2146 (RSA) • iio 650 s-i 115 2.1 7 603 6 2 8 9-3 1.5 6 i: 639 32 5 2.9 6.7 11 i c ea bisbopii Rock Carlquist 55.S (RSA) 564 8 E 6 1 26 5 5.6 12 62 1.8 B E 480 31 5 2.4 .0 107 187 1.8 Carlquist 568 (RSA) 545 553 19 62 2.1 6 C 477 36 5 >5 •1.1 39 5 >5 8. ' ea carhonii Rock Carlquist 590 (RSA; Root 146 86 109 2.1 " B 581 583 "1 109 2. (. 1 688 32 3 > 10 12." Cyanea (Ofiacea (A. Gray) Rock var. 86 130 2.2 5 C 905 3. 7 >5 .0 fmriei (Levi.) B. Wimmer Carlquist I '62 (RSA) - 2 " " C 887 •,1 6 3.5 11.0 604 155" Hi 2.1 1: 995 J4 6 4.4 12.2 98 156 3.1 Vw 26 (50 658 60 2.1 E 780 32 5 >10 11.3 88 3.3 8 1. 712 32 5 3.0 5.5 74 112 9 Cyanea gay ana Rock Carlquisi 19 '6 (RSA; 650 LO C SK) U •i > io 12.5 413 67 90 1.6 5 E 893 26 3 2.6 8.2 59 80 1.6 a grimesiana Gaudich. Carlquist 2 I CO ( RSA | 728 - 888 41 5 >10 5 ' 88 2.2 C 802 26 5 3.8 10.6 80 114 1.7 c Cyanea bardyi Rmk Yw 2( 477 soo 64 8 802 32 7 1,1 9-8 78 2.3 6 C 882 :8 5 2.1 4.4 100 147 2.9 c 100 2.3 8 i: 811 31 6 >5 9.1 b 68 Abbreviation of wood collection follows usage in Index xyUrionm: W. L. Stern. 1967 Kcpnum Vegetable 49: M6. Utrecht. 87 125 L9 6 E 876 2- 3 >5 6.5 A. Stalleu (eds.) ed. 5. 1964, Resnum VeRerabile 31 1-251. Utrecht •- NAME COLLECTION > Cyauea leptosteg/a A. Gray Carlquist H-4 (UC) 513 733 66 104 2.1 8 C 910 33 6 1.7 9.5 Carlquist 1795 (RSA) Inside Base 613 928 83 112 2.3 ll C 905 36 6 ;,'•; lo 5 Carlquist 1795 (RSA, Outside HUM- 526 812 9 11 i 1.8 8 c 880 28 - 2.8 6.4 Carlquist 1795 (RSA) Upper Stem 746 10 9 -i 108 16 c 1119 38 s >5 6.6 Carlquist 1961 (RSA, 521 784 73 113 2.4 •i c 868 \\ 5 (..9 -.9 Cyanea longipeduni ulata Rock Carlquist 610 (RSA) 650 893 i 64 1.6 10 c 8 5 32 5 1 I 5.7 Carlquist 22i6 (RSA) 472 851 5s 83 2.6 6 c 690 26 3 2.0 11.6 Cyauea macroslegia Hillebr. Carlquist 569 (RSA, (90 705 78 112 l 5 8 743 35 5 .'.() 8.6 c ; Cyauea marksii Rock Carlquist 593 (RSA) 481 81 J 63 l.~ l i c 1006 J 8 2 - J 9 Carlquist 2075 (RSA) Base 174 706 57 80 l 1 6 E 3 u 8.0 Carlquist 2075 (RSA) Upper Stem 486 90 ' (.i 90 1.7 1 E 950 25 - J.l 6.H Cyauea pilosa A. Gray Carlquist 1858 (RSA) 501 908 50 70 1.5 8 c 691 29 6 2 i A '• Carlquist 2040 (RSA.) 657 1008 62 83 I 9 6 c 957 J 2 6 M 4.6 Cyauea recta (Wawra) Hillebr. Carlquist 1758 (RSA) 552 61 88 1.7 6 c 890 \6 5 4.6 11.6 Carlquist 1990 (RSA) 60s 885 63 88 2.1 5 c 958 33 5 > 10 5..S Cyanea shipmaiiii Rock Carlquist 2121 (RSA) Base [10 616 6 100 2.7 9 E -60 28 6 2.0 4.9 Rock 25619 (BISH) Upper Stem 460 615 59 88 2.9 6 E 774 32 4 >5 6.7 Cyauea solenncalyx Hillebr. Carlquist 2222 (RSA) 510 19 58 95 1." 8 V 848 28 5 4.3 12.3 Cyanea stictophylla Rock var. inermis Rock Carlquist 589 (RSA) 381 611 78 104 l.s 8 C 771 38 4 >5 10.3 Cyanea sylvestris Heller Stern & Carlquist 1335 (US, RSA) 564 738 55 94 2.8 6 I 942 v, 5 5 7.8 Cyanea tritnmantha A. Gray Carlquist 601 (RSA) Adult 586 754 91 135 1.1 6 E 969 it 5 >5 6.6 ; Carlquist 602 (RSA) Juvenile I I ! 677 56 78 1.4 E 887 m 4 >5 6.7 Carlquist 2245 (RSA) 539 851 85 128 1.8 Ki I 980 il 4 >5 6. ' S|[33 --J 3lBU3Sq:|nuJ qipr,x\ ~ X nI ON CN O O ON IUUI 'sSwaxe 's&ei aivusspfntu iipnn r-i rr, — ri ri A ri A A r4 rn in —' A — ~ CN CN — tc ,\ 7/ 'sn'rJOAi: 'sjoqij lujojuqn 'sircM ss.->u>piqj^ r, x? 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D--_ o••* , *>»a • > -- * -^ — D§ E I '•n S. ar s 8 E i i- r r fe. •5.; 8" K l 1' t li B- 0 f I ! ~ a 7- ? r JtJ g •- • r x Cd£ D ~ - 1- = | — T. ° 2 ~ -- n r. n n n n n .< w-^s-nnnnn b » n & fe to ,. fPPBbMBIO -l-^-^-n-nn < *— -n -i «-i «| -n 3 3 « ~ — c i- ui i- j - ^ *» 3Pr - r3t 2-i — — _ — •** o ,sj ^ w ,-> ° ^ §! £ - x -" = ° — g Sn ~ S SO * | «~ * H 5 £ £ '-" J 1 i 1 ^ —. _.- kjJ JJ _ _" ^ ^- ^ :Sc- = S 3 -IT IS - C tj Vessel element length, average, n 00 VO O M O S ui - —N J.-. I C C oi ^1 ^o'^-^ £ C§ gtt J - _ 5 & Longest vessel clement, /i \_n \_NAC ^ S £ fC S ^. ^ - ^ u. ^ u) ^ Vessel diameter, average, g 2 2J rrl & ^2 X! f i! 9SS2 2 lo ^ "^ Widest vessel, g i- X UJ CN C\ K Ji. BN &0 O X O C\ Q> • per group «J V< -o; -J -~1 ON Cv\ O -~J C\ --J --ICCOCC— lo i— C\ Diameter pits, average, g Vessel pits mostly circular (C) or nnrsrinrs n n nw n m rr M w elliptical (E) -J\0>00 CC M o \j\ Kj\-~i O O ^O v-/< C\ , ,., .r ,., ^! — *£ "1 c\ "-J S x c^ - _. : y: 3 Lentrth libriform fibers, averace, /^ UJ W UJ A. IO Ivj K) W WUi 'JJ UJ UJ VJ U) niimpfpr likrifnrm fihprq avpraop U M vi ui w \o \c oo o »-J ui ^Os wv» uiameter anrnorm tioers. av< rage, /- Thickness walls, libriform fibers, ^ Ui JJ ifc. k/i i, ^, U Jlrb-UI Ul CV i^ i^ average, f- IO lo £>. 'vu — IsJ lo — — to __ WW O O •~n O Cs -i. --1 O \oOl O VA Ul U> VI Height multiseriate rays, average, mm y- y — c^ i-N i ex _ — ,/- — y p p o- -: i>. cc - c* -. -1 ~ — ^; — O. r- -" ~C Width multiseriate rays, average, cells LITERATURE CITED BROWN, F. B. H. 1922. The secondary xylem of Hawaiian trees. Occas. Pap. Bernice Pauahi Bishop Mus. 8(6): 1-157. CARLQUIST, S. 1958. Wood anatomy of Heliantheae (Compositae). Trop. Woods 108: 1-30. . 1960. Wood anatomy of Cichorieae (Compositae). Trop. Woods 112: 65-91- . 1961. Comparative plant anatomy. Holt, Rinehart and Winston. New York. . 1962. A theory of paedomorphosis in dicotyledonous woods. Phytomorphology 12: 30—45. . 1966. Wood anatomy of Compositae: a summary, with comments on factors controlling wood evolution. Aliso 6: 25-^4. . 1967. The biota of long-distance dispersal. V. Plant dispersal to Pacific islands. Bull. Torrey Bot. Club 94: 129-162. . 1970. Hawaiian natural history. Natural History Press. New York. CUMBIE, B. G. I960. Anatomical studies in the Leguminosae. Trop. Woods 113: 1-47. HAUMAN, L. 1933. Les "Lobelia" geants des montagnes du Congo Beige. Mem. Inst. Roy. Colon. Beige, Sect. Sci. Nat. (8°) 2: 1-52. HBDBERG, O. 1957. Afroalpine vascular plants. A taxonomic revision. Symb. Bot. Upsal. 15: 1—411. . 1964. Features of Afroalpine plant ecology. Acta Phytogeogr. Suec. 49: 1-144. KRIBS, D. A. 1935. Salient lines of specialization in the wood parenchyma of dicotyledons. Bot. Gaz. 96: 547—557. METCALFE, C. R., AND L. CHALK. 1950. Anatomy of the dicotyledons. Clarendon Press. Oxford. RECORD, S. J., AND R. W. HESS. 1943. Timbers of the New World. Yale Univ. Press. New Haven. ROCK, J. F. 1919. A monographic study of the Hawaiian species of the tribe Lobeiioideae family Campanulaceae. Mem. Bernice Pauahi Bishop Mus. 7(2): 1-394. WIMMER, F. E. 1953. Campanulaceae—Lobeiioideae. Teil II. Das Pflanzenreich IV 276b (107 Heft). Akademie Verlag. Berlin. . 1956. Campanulaceae—Lobeiioideae. Teil I. Das Pflanzenreich IV 276b (106 Heft). Akademie Verlag. Berlin. YDRAC, F.-L. 1905. Recherches anatomiques sur les Lobeliacees. Thesis. Imprimerie Lucien Declumb. Lons-Le- Saunier. 72 Carlquist