Biological and Morphological Aspects of the

Edward S. Ayensu

Biotropica, Vol. 5, No. 3. (Dec., 1973), pp. 135-149.

Stable URL: http://links.jstor.org/sici?sici=0006-3606%28197312%295%3A3%3C135%3ABAMAOT%3E2.0.CO%3B2-E

Biotropica is currently published by The Association for Tropical Biology and Conservation.

Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use.

Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/journals/tropbio.html.

Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission.

The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academic journals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers, and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community take advantage of advances in technology. For more information regarding JSTOR, please contact [email protected].

http://www.jstor.org Wed Jan 23 08:49:56 2008 Biological and Morphological Aspects of the Velloziaceae

Edward S. Ayensu Department of Botany, National Museutn of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A.

ABSTRACT

Recent field and laboratory observations are the basis of a review of various aspects of the biology of the Velloziaceae. Some of the pollinators of the flowers have been identified. Fruit, seed and seedling morphology, rate of germination, phenology, the effect of rainfall on flowering as well as the effect of ecological shift on the habit of the species have been studied. Attention is drawn to the future survival of the Velloziaceae in view of current destruction of the areas in which the grow.

THE VELLOZIACEAEis one of the most interesting ing of the leaves in response to water loss from the families that occurs in Africa and South Ameri- mesophyll. The leaves of most of the South Ameri- ca on account of the difficulties surrounding its ge- can species of Barbacecia do not have furrows, al- neric limits and its distributional pattern. The fam- though a few such as B. irwifziafza have them on the ily contains about 250 species of perennial herbs and abaxial side. Barboceniopsis boliviensis and B. shrubs. The type Vellozia Vand. contains vmgusiuna have furrows on both surfaces as do the the largest number of species with approximately Old World species with barbacenioid features (Ayen- 140, followed by Barbacefzia Vand. with about 70. su 1968). Another adaptation against water loss Juss. with about 38 species includes all is revealed by a longitudinal section through the the Madagascan and African species, except for Tal- stem which shows that the bulk of the mass consists botia elegafzs Balfour which occurs in South Africa. of persistent leaf sheaths surrounding a slender The habitats in which the Velloziaceae grow in the woody stem. Apart from the slender stem and its Malagasy Republic, southern Africa, and South lateral branches, there are long aerial roots that are America are more or less similar. Most species are completely encircled by leaf bases. The roots grow lithophytes, growing in stony places such as on ex- down through the entire length of the main stem posed granite rocks, but some are found on dry until they reach the ground, where they spread out plains in alpine environments. For example, among and assume the normal role of anchorage. The long the Brazilian members, Vellozia cafzdida and V. aerial roots grow rather rapidly because the leaf plicata grow on barren soil while Burbacenia par- bases that encircle them help in the maintenance $area prefers humus on rocks. The plants have be- of an ideal microclimate. When the leaf sheaths are come adapted to highly variable climatic conditions, removed from an uprooted Xerophyta, Vellozia or for during the day they are subjected to intense solar Barbace.nia, the aerial roots are especially moist and radiation but occasionally the sunny conditions give may be dripping with water even though the plants way to short but violent rainstorms. At night there are growing in a dry habitat. The water-holding is often dense cloud cover which provides enough capacity of the leaf sheath is demonstrated by re- condensation to moisten the plants and, to a lesser moving one from an herbarium specimen and plac- extent, the substrate. ing it in water or a wetting agent such as Aerosol Many plants in xeric environments have succu- OT Solution (Ayensu 1967). It absorbs the medi- lent leaves which help reduce the rate of transpira- um rapidly as if made of blotting paper. tion as in the cactus-like euphorbias, succulent mela- stomes, and many bromeliads that grow in the same TAXONOMIC REVIEW habitats as the Velloziaceae. The leaves of Vellozii? Earlier authors like Kunth ( 1822 ) confused the Vel- have developed a mechanism for regulating transpir- loziaceae with the Bromeliaceae because of strong ation by the reduction of the rate of water loss per resemblances in habit. The primary classification unit area and/or by the contraction of the transpir- was based on three sets of characters: presence or ing surface area. The rate of transpiration is re- absence of a perianth-tube above the ovary, number duced by the placement of the stomata in abaxial of stamens, and type of filament. Baker (1875) furrows in the leaves. These furrows permit con- and Hutchinson ( 1934) also relied on the presence tractions, inrolling, outrolling, and lengthwise fold- or absence of an extension of the perianth-tube above the ovary as a key character. Although this and Bu~buce?zioides). Almost all species in the sec- reliance is valid at the extremes, it is not infallible. tion Vellozioides occur in Arabia, Malagasy Republic, Pax (1887) used the distinction between six sta- southern Africa, south West Africa, and Nigeria mens and more than six stamens as an important while most species of Bn~bnce?zioik?esoccur in East character. Again such a distinction works well with Africa. most of the species, but it places under Burbaceniu The development of large translucent cells above species that in every other respect are indistinguish- the abaxial sclerenchyma girders and sometimes sub- able from VellozM. It is additionally misleading jacent to the abaxial epidermis along its entire because in some species with nine stamens the petals length is quite common in species of New World subtend a single stamen, as in Bu~buce?zia,whereas Velloziaceae. In the Old World species, such trans- in other spec& they subtend more than one, as in lucent cells are mostly absent, bur in some species Velloziu. Seubert (1847) used the form of the fila- they occur between vascular bundles near the adaxial ment in conjunction with other morphological char- and abaxial epidermal surfaces. The water-holding acters to separate the genera. Basifixed anthers with capacity of translucent cells is well known in various elongate fiiaments were attributed to Vellozia and plants in which such cells occur, and their im- dorsifixed anthers with short filaments assigned to portance may be ascribed to the environmental con- Burbacenia. Smith's classification ( 1962 ) of the ditions to which the plants are subjected (Diogo New World Velloziaceae was essentially a refine- 1926). ment of Seubert's work based on a study of more Floral Anatomy: Unlike the vegetative anatomy, the species. floral anatomv of the Velloziaceae has been little In earlier publications (Ayensu 1968, 1969a, explored, and our general knowledge of the repro- 1969b, 1973) emphasis has been placed upon the ductive anatomy of this family is quite meager. Re- systematic importance of three types of sclerenchyma cently Dutt ( 1970) reviewed the earlier embryologi- patterns associated with the vascular bundles in the cal snidies made by Stenar (1925) on Velloziu ele- leaves. The Vellozia-type refers to species whose gmzs ( =Talbotia ) , Bnrbuce~ziaf i.agru?zs, and Vellozia adaxial sclerenchyma is generally inverted crrscenti- conzpacta. Dutt noted that the embryo sac in Bnr- form or cap-shaped and abaxial sclerenchyma either bnce?ziu. bicolor and Vellozia elegafzr is of the 'Poly- U- or Y-shaped. The Burbuce.~liu-typeis found in gonum' type. One feature of interest is the develop- species where the adaxial side of the vascular bundle ment of an integumentary tapetum formed by the has an inverted Y-shaped sclerenchyma girder and inner integument. Furthermore, he observed that the abaxial girder is either Y-shaped or three-pronged an obturator is developed from the funicle. How- (the flanges of the Y's do not meet directly but ever, Stenar's study lacked details regarding fertiliza- contact is made by thin-walled parenchymatous tion, endosperm development, and embryogeny. cells). The Xerophytu-type occurs in species where On the basis of Stenar's study, Dutt remarked the vascular bundles are accompanied on the adaxial that embryologically the Velloziaceae resemble the side by an inverted crescentiform or V-shaped cap Amaryllidaceae. Of special significance is the de- while the abaxial sclerenchyma is a U- or W-shaped velopment of a funicular obturator in Vellozin gar- cap. Because of recent taxonomic changes (Smith pztrea and the amaryllidaceous species Bo772areu cald- and Ayensu 1974) and further anatomical studies asii. On the basis of this observation Dutt stated, of the New World species (Ayensu 1974), this "Therefore, it appears a matter of opinion whether type is now referable to the Madagascan species and to include the two genera Vellozia and Ba~bace?ziu a few vellozias. The mesophyll, on the other hand, under the Amaryllidaceae or to group them together is of two types: (a) dorsiventral, with distinct pali- under a separate family, the Velloziaceae, consider- sade and spongy tissues, and (b) isolateral, that has ing the xerophytic nature of the plants, the dichoto- not differentiated into palisade and spongy tissues. mous branching of the stem, the branched nature of All the Old World species classified under Vellozia the stamens in most species, and the stalked and and Xeroghytu which I listed earlier (Ayensu 1969) thickened placentae in the ovary " and the American species of Velloziu have dorsi- In earlier taxonomic treatments (Pax and Hoff- ventral mesophyll patterns while species of Ba~ba- man 1930; Durand and Schinz 1895), Velloziaceae ce?zia have isolateral mesophyll. Under the newly was treated as a tribe under Amaryllidaceae. Recent proposed classification of the Velloziaceae, based preferred treatments consider the Velloziaceae as a partly on leaf anatomy (Smith and Ayensu 1974), distinct family. However, "The xerophytic nature two genera accommodate the Old World species: the of the plants" and "the dichotomous branching of monotypic genus Tnlbotia and the polytypic Xero- the stem" which Dutt indicated are poor characters phytu (with three sections, Xeroghytu, Vellozioides. for considering this as a family separate from the

136 Ayensu Amaryllidaceae. The branching which occurs in vantage for self-compatibility within each species. some species of Velloziaceae is not dichotomous: On the other hand, there might be great constancy the branches are ordinary bifurcations as occur in in pollinators. Experimental studies on self-com- many plant families. he 3-chambered ovary with patibility and on sterility will provide answers to many ovules is characteristic of both the Velloziaceae these observations. and Hypoxidaceae (Ayensu 1973). Pollination: Pollination in this family appears in The only other published works on the reproduc- general to be allogamousl but may be either geitono- tive anatomy of the family that focus on floral vas- garnous' or xenogamus%r both. Furthermore, the cularization are those by Noher de Halac (1969, Velloziaceae seem to be homogemous,4 so potentially 1971) on Barbace+ziopsis bolivie?zsis, who in 1971 the flowers can be self-fertilized. suggested that the petaloid appendages represent During a visit to Brazil in 1972, species of Vel- staminodes. lozia were seen to be visited by the following five Pollen Morphology: The morphology of the pollen species of bees, belonging to four families: Apis in the Velloziaceae promises to be a very important mellifera, the common honey bee, which originated systematic feature of the family (Erdtman 1963. in Eurasia or Africa and has been introduced to the Maguire 1969). Vellozia has united tetragonal rest of the world; Euglusia pztrgz~~ata(fig. 2d), a tetrads and non-aperturate pollen, while Barbace?zia semi-social or solitary New World bee; Aagochlora has simple ellipsoidal monosulcate monads. nzetallica (fig. 2c), a semi-social New World bee In a recent snldy of a total of six species of Vel- with a bright metallic blue head and thorax; the 2ozia and Barbacenia (Ayensu 1972) the generic world-wide Megachile curvqes (fig. 2a), which is differences in pollen types held up, and it became solitary and commonly known as the leaf-cutter bee; quite clear that the exine of the pollen walls ex- and Psae?zythia spp. ( fig. 2b) , a New World solitary hibited species-specific characteristics. The exine bee. sculpturing of Vellozia is frequently described as All the bees named above presumably collect reticulate or vermiform-reticulate, but in some spe- Vellozia pollen as their basic food since it is more cies the pollen is neither reticulate nor vermiform- abundant than nectar, and (to human taste) the nec- reticulate. In Barbace9zia the pollen walls are reticu- tar produced by Vellozia flowers does not seem as late. However, there are easily recognizable varia- sweet and as concentrated as that produced by Bar- tions in the reticulations, size of the muri, and pres- bacefzia flowers. Bavbace?~iaflowers were seen to ence or absence of ~rotrusions. be frequently visited by Canzponotus (fig. 3, bot- There is a clear correlation between the Barba- tom row, center), and carpenter ants, but not by cefzia-type of pollen and the shape of the stigma of bees, though Sazima (1972) reported that he ob- all the Old World species of Velloziaceae and Bavba- served small-sized Hymenoptera of the bee families cenia. The stigma of Barbacenia. Xeroghyta, and Colletidae and Halictidae on Bmbacenzd and Ayl- Talbotia is capitate or clavate while that of Vellozia thonid. One possible explanatton for the low in- is very prominently horizontally 3-lobed. Pollen cidence of large bees visiting Ba~baceniuflowers is grains of the Barbace9zia-type measure about half the that plants of Barbace~iaproduce very little pollen size of the grains in Vellozia. in comparison with those of Vellozia but superior In an attempt to evaluate the stigma-pollen cor- nectar. The ants are, therefore, much more likely relation within each species, I examined several to concentrate on Barbacenia flowers for their food whole stigmas of both Vellozia and Barbacenia with than on Vellozia. Furthermore, the ants can easily the scanning electron microscope (fig. 1 ) . Figure 1 carry Barbacenia pollen (which is about half the shows the type of pollen as well as the points of average size of Vellozia pollen) from the anthers pollen attachment to the stigma. In every case, ex- to the stigma while in search of nectar and thus cept one, the pollen found on the stigma was of the might be effective pollinators. The concept of ant same species as the receptor plant. A couple of pollination is a controversial one and requires strin. grains of Compositae, mixed with Vellozia pollen, gent observations before conclusive statements can were found on one stigma, but this appearance is be made. assumed to be a chance wind-blown denosit. The The principal observed predator of visitors to apparent specificity of pollen-stigma syndrome is a Velloziaceae flowers is an assassin bug (Reduviidae). clear demonstration of the successful breeding sys- As soon as a flower of Vellozia opens, the assassin tem that characterizes the species. The fact that in :The flower is pollinated with pollen from another flower. nearly every case the pollen grains on the stigma on -The flower is pollinated by another flower of the same which they are affixed belong to the same species plant. "he flower is pollinated by pollen from another plant seems to suggest that there is a strong selective ad- "0th stigma and anthers mature simultaneously.

Biology and Morphology of Velloziaceae 137 FIGURE 1. Scanning electron micrographs showing pollen attachment to stigma and details of pollen shape and surface. a,b,c, Vellozia abietina Hatschbach 30136, (a) x67, (b) x334, (c) ~1000.d,e,f, Barbacenia gentianodes Hatschbach 30075, (d) x40, (e) x400, (f) x2000.

138 Ayensu bug takes its position by lodging quietly on the indication of the natural solitary behavior of the abaxial side of the tepals. When a bee visits the predator or may be due to the scarcity and the dif- flower the assassin bug waits until its prey is within ficulty of obtaining food. Such situations may tend a comfortable reach before it strikes with its front to encourage predator territorialism. legs. When the bee is totally incapacitated, the as- Flower Constancy: Flower const'ancy in the collec- sassin bug gradually lowers the prey to the ground tion of pollen or nectar is a characteristic of bees to feed on it. Two assassin bugs are seldom ob- and to some extent ants. This phenomenon falls into served on one plant. This situation may be an two inajor categories: (a) the insects make succes-

FIGURE 2. Some of the bees observed in association with Vellozh flowers. (a) Megachile cwvipes (11.5 rnrn long), (b) Psaenytbia spp. ( 14.5 rnrn long), (c) Aagochlora metdJica (8-12 mm long), (d) Elcpksia pa~fiwda( 15.5 rnrn long).

Biology and Morphology of Velloziaceae 139 sive trips to gather almost pure pollen from one suggest that the specificity of bee visits to any one particular kind of plant, or (b) the insects concen- species lasts only as long as that particular species trate on collecting pollen from two or three kinds is in flower. Once another species begins to flower, of plants. Some of the bees that are generally con- the pollinators turn their attention to the new flow- sidered oligolectic5 often visited other plant fami- ering species, thus creating a short-lived host-speci- lies. Afiis mellifera and Aagochlora metallica, for ficity phenomenon. Most flowers that are pollinated example, visited stigmas of Vellozia and Xyris by bees have certain characteristic features that en- flowers alternately. The data in table 3 show that able them to be recognized. Those features include different species of Velloziaceae flower throughout brightly colored petals or tepals which are usually the year, an irregular flowering pattern which may yellow, purple, or blue, and an attractive scent. In Vellozia the bees use the stigma as the landing plat- Bees that collect pollen consistently from a single plant species or a group of related species. form, and the tri-lobed stigma in Vellozzh (fig. 3)

FIGURE 3. Top row from left to right: variation in flower color in Vellozia epidenriroides, (left) white, (center) white-purple, (right) purple. Middle row: (left) Vellozia carzlncularis with a bee collecting pollen; (center) a group of Vellozia glabra flowers, one being visited by a bee; (right) Vellozia phalocarpa showing the effect of fire on the leaf-blades. Bottom row: (left) Bmbace~tia gentianoides growing on bare rock; (center) Barbacenia inuolucrata being visited by Cmponotus ants; (right) two large populations of vellozias.

140 Ayensu is so conspicuous that if it is removed,' bee visitation TABLE 1. Dimensions of seed capsr~les of some New to that particular flower is sharply curtailed, even World Vellozia and Barbacenia. though the bright-yellow or purple tepals and sta- mens are in position. On the other hand, if the Length (cm) Width (cm) stamens and the tepals are removed but the stigma V. abietina - Mart. 0.5 is left in position, the bees land on it but are V. alata - L. B. Smith 6.5 balked by the absence of other parts. A fuller as- V. brevifolia - Seubert 1.5 V. brevisc@a - Mart. ex Schult. f. 1.5 sessment can only be made after a careful study of V. caruncularis - Mart. & Seubert 1.2 the visual acuity of the bees and the ultraviolet pat- V. compacta - Mart. ex Schult. f. 3.2 V. coro?zata - L. B. Smith 3.8 terns of the flowers. V. crassicaulis - Mart. ex Schult. f. 2.0 Longevity of the Flower: Flowers of Velloziaceae V. dasypus - Seubert 1.5 V. declinans - Goeth & Henr. 1.1 frequently open in the morning, just about the time V. epidendroides - Mart. ex Schult. f 1.0 that the bees begin to forage. After several bee V. glabra - Mikan 3.1 visits, the flowers begin to shrivel, having lasted V. hatschbachii - Smith & Ayensu 3.0 V. hirsuta - Goeth. & Henr. 1.7 about half a day. If the flower opens in an ob- V. i?zcurvuta - Mart. ex Schult. f. 1.6 scure place and is not visited by bees, that flower V. lacpa - Smith & Ayensu 1.7 V. nuda - Smith & Ayensu 1.9 remains open and fresh through the entire day or V. ornata - Mart. ex Schult. f. 1.5 longer.- If buds were covered with straw the eve- V. plicata - Mart. 1.0 ning before they were due to open, the flowers V. riedeliana - Goeth. 81 Henr. 2.5 V. scoparia - Goeth. & Henr. 0.3 stayed open and fresh for a long time the following V. taxifolia - Mart. ex Schult. f. 0.9 day. There is a parallel of this phenomenon in or- V. 5.avhbilis - Mart. ex Schult. f. 3.0 chid flowers. Experimental studies on Vmdu (Dijk- B. cot/iscortigma - Goeth & Henr. 8.0 man and Burg 1970) and Cymbidium (Arditti and B. fiava - Mart. ex Schult. f. 2.3 Knauft 1969; Arditti, Flick, and Jeffrey 1970) have B. fulzma - Goeth. & Henf. 4.0 B. i?wolr~crata- L. B. Smith 7.7 demonstrated the changes that orchid flowers under- B, longiflora - Mart. 1.3 go after pollination. Self-pollination in Vanda Rose B. longiscapa - Goeth. & Henr. 1.2 Marie (V. hookeriam albo x V. teres alba) induces B. riedeliana - Gceth. & Henr. 1.0 ethylene formation within one hour and flower fad- ing within eight to ten hours. In Cymbdiam it was Some have almost smooth surfaces like Vellozia observed that the application of abscisic acid induced i~lutu,V. hatschbachii, V. glabm, V. omto, V. in- some of the post-pollination symptoms. It is pos- curvuto, and V. abietina. Others are covered with sible that pollination in Velloziaceae induces ethy- bristles, as in V. lappu, V. crussicaulis, and V. nada. lene or auxin formation within a few hours which Still others are covered with glandular-like projec- results in the wilting of the flowers. tions, such as in V. coro~zutu,V. breviscapa, V. carun- Variations within Species: In the Planalto of Brazil cularis, and V. plicata. there are three color varieties of the flowers of Vel- The seed capsules are characteristically sticky, lozio epidendroides: white, purple-white, and purple especially when atmospheric dampness mixes with (fig. 3, top row). These variations could be due the gummy substance that is present on the capsules to either environmental or genetic differences, but of all species. The stickiness is probably associated the altitude and environment in which the three with dispersal by birds, cattle, or man. The surface variations grow are so similar that any changes in of the capsule becomes dry just before rupture. temperature and humidity affect all three alike, and The dried seeds of Tulbotia elegans bear distinc- no anatomical differences were detected that corre- tive hooks (fig. 5a, b) which are similar to the late with the colors. Thus the cause of the variation barbs on the seeds of some Compositae. The sig- is not known. nificance of these hooks is not known, but such a Fruits and Seeds: The seed capsules or fruits of Vel- feature may enhance dispersal. Xerophytu uiscosa, while having a more or less stratified coating, has loziaceae come in a variety of sizes (table 1) and lost its hooks (fig. 5e, f). None of the seeds of the shapes (fig. 4). Figure 4 A-G represents a range New World species have hooks (fig. 6). of seed capsules in Barbaceniu. The capsules are lightly covered with bristles as in B. fulva and Seedling Morphology: In a comprehensive survey B. involacruta or glandular emergences as in B, con- of seedling morphology (Boyd 1932) iscostig~nu,B. Lo?~gifLoru,B, fluoa, B. riedelima, and Tailboth (Vellozio) elega~swas the only species of B. longiscapu. In Velloziu (fig. 4 H-DD) there are Velloziaceae described. In this study seeds of 13 three types of surfaces that characterize the species. species of Vellozia, three species of Xerophyta and

Biology and Morphology of Velloziaceae 141 FIGURE 4. Seed capsules of Velloziaceae showing the variety of forms, sizes, and surface characteristics. Scale Xx. (a) Barbacenia fulva, (b) B. coniscostigma, (c) B. involucrata, (d) B. longiflora, (e) B. flmva, (f) B. riedeliana, (g) B. longisc@a, (h) Velloziu compacts, (i) V. coromta, (j) V. riedeliana, (k) V. glabra, (e) V. data, (m) V. hatschbachzs, (n) V.crassicaulis, (0) V. variabilis, (p) V.&pa, (q) V. breviscapa, (r) V. declinans, (s) V. epiden- droides, (t) V. caruncularis, (u) V. oryata,, (v) V. plicata, (w) V. taxifolk, (x) V. nda, (y) V. hirsutca, (2) V. incurvata, (aa) V. dasypus, (bb) V. brevzfolza, (cc) V. abietina, (dd) V. scopmia.

142 Ayensu FIGURE 5. Scanning electron micrographs of seeds showing details of seed shape and surface sculpturing. Talbotia elegans Gaff s.n. (a) x36, (b) x720 (note hooks on the seed surface). Xwophyta villosa Gaff s.n. (c) x22, (d) x126 (note circular hilum). Xwophyta viscosa Gaff s.n. (e) x72, (f) x172 (note lack of hooks on seed surface). Vellozia glabra Maguire 49100 (g) x32, (h) x132 (note elongate hilum).

Biology and Morphology of Velloziaceae 143 FIGURE 6. Scanning electron micrographs of seeds showing details of seed shape and surface sculpturing. Vellozia abietina L. B. Smith and Ayensu 15979 (a) x80, (b) x500. Bmbacenia longiscapa Irwin et al. 22186 (c) x40, (d) x146. Vellozia darypus L. B. Smith and Ayensu s.n. (e) x20, (f) x200. Barbacenia paramensis Hatschbach 29212 (g) x40, (h) x212.

144 Ayensu two of Bmbacenia were successfully germinated (figs. TABLE 2. Rates of germi~zatio~z of some Barbacenia, 7-10 illustrate stages of seedling development in Vellozia, Xeraphyta, ad Talbotia. Vellozia and Barbacenia). The seeds were sown on soaked foam-like pads in a Sherer Model CEL 255-6 growth chamber at a constant 24-hour temperature Number of days to of 30+ loC (86" F) and subjected to 14 hours of wU germination for various - w percentages of seeds sown light and 10 hours of darkness under 200- to 300-foot 8 % candles of cool white fluorescent illumination 60 cm from specimens. The primary root, covered with root hairs, emerged in about 10 days and two to three days later the first foliage leaf began to appear. B,paraizae~zsis 20 8 Further development differed between species; in Hatschbach 292 12 B. inzolucrata 20 8 some there was rapid production of leaves while the Smith & Ayensu 15999 tapering primary root appeared to be somewhat B. iiivolz~crata 20 14 dormant, in others there was a burst of lateral rootlet Smith & Ayensu s.n. development while the leaves appeared mfted. B. inzolz~crata 20 10 In general, the development of Velloziaceae seed- Smith & Ayensu 15941 lings, as illustrated by figures 7, 8, 9, and 10, may V. tz~biflora 10 be termed fairly uniform and corresponding to Ayensu s.n. Boyd's type A. V. crassicaulis 10 10 Smith & Ayensu 15978 Rate of Germination and Seed Viabilitv: The data V. or?iata 20 10 in table 2 are derived from seeds germinated four Smith & Ayensu 15993 months after collection, having been stored in en- V. dasjpz~s 14 9 Smith 16018 velopes at room temperature. About six months V. wda 20 10 later more seeds were germinated and viability had Smith & Ayensu 16000 dropped to 60 percent. After 13 months some seeds V. hatschbachii 20 10 were still viable. Seeds of some of the species did Smith & Ayensu 16002 not germinate at all, some took twice as long as V. epzde~zdroides 20 10 others under the same conditions of light, tempera- Smith & Ayensu 1597 1 ture, and humidity. However, the time for the V burle-marxzi 2 0 12 seeds to lose viability is long enough that the seeds Sm~th16017 could be transported many miles. If the longevity V. decliizans 20 8 Smith & Ayensu 15990 of the larger (0.5-1.8 mm) seeds of Old World V. or?iata 2 0 9 species is comparable, then the copious endosperm Smith & Ayensu 16001 they contain, together with the hard seed coat, should V crass~caulis 20 10 insure wide dispersal by air flotation or bird dis- Smith & Ayensu 15947 persal. V. alata 10 8 Smith & Ayensu 15951 Phenology of the Family: The periodic flowering V. z ariahzlis 20 10 and fruiting of many tropical and subtropical plants Smith & Ayensu 15981 has been poorly monitored, either because it is as- V. crajsicaz~lis 20 10 sumed that there is continuous flowering and fruit- Smith & Ayensu 15965 ing throughout the year, or because the timing of V, iticurzata 20 10 tropical expeditions is based upon flowering and Smith & Ayensu fruiting data obtained from past collecting records. V. hrecifolia 20 9 As a result, published opinion on the frequency of Smith & Ayensu 15966 flowering and fruiting of a particular species of V. tnxifoiia 10 10 Sniith & Ayensu 15970 plant is often inaccurate. Botanists in the East Afri- T. elegaizs 10 5 can Herbarium have confirmed that in East Africa Gaff s.n. the flowering of a number of species of Velloziaceae X. hz~mills 20 10 occurs a few days after heavy rain. Table 3 lists the Gaff s n. flowering months of several species of African Vel- X, ciliosa 10 5 loziaceae. Of the 24 specimens of Xe~ophjta Gaff s.n. schnlzleinid, flowering has been recorded in every X. z,iscosa 20 5 month except January and November. In Xevoph~ta Gaff s.n.

Biology and Morphology of Velloziaceae 145 spekei, also based on 24 specimens, flowering has pollinators may affect fruiting, but nothing is known been recorded in every month except July. It seems of the pollinators of the African species. from these and other data in table 3 that flowering In a study of flowering plants in southern Africa, in the Velloziaceae occurs throughout the entire year. Gaff (1971) pointed out that few plants possess The absence of flowering records in the months in- mature foliage that is tolerant to desiccation. In- dicated may be due to lack of field collecting at cluded in his study were the following species of those times rather than actual absence of flowering. Velloziaceae: Xerophyta clavato, X. retineruis, X. There is a need for the collection of phenological ha?1?Jilis, X. V~SGOS~,and X. sqmrrosa. In a private information for accurate interpretation of the over- communication, Dr. Gaff noted that "this (1971 all ecology of the family. For example, a shift in publication) was only intended to be a preliminary climatic conditions may affect flowering in any one note . . . determinations on two Xerophyta species year. Furthermore, a shift in the life cycle of the made since then gave drought tolerances of approxi- mately 10% relative humidity for X. sgmrrosa and 5% for X. clauata. . . . Angiosperm desiccation- tolerant plants vary in their reaction to stress in that

FIGURE 7. Vellozia alata L. B. Smith and Ayensu 15951. (a-e) stages of seedling development, (f) diagram of FIGURE 9. ~ ~ involucrata~ L, bB, smith~ and ~ ~ ~ h whole seed, (g) transverse section of seed coat. Ayensu s.n. (a-f) stages of seedling development, (g) diagram of a seed, (h) transverse section of seed coat.

FIGURE 8. Vellozia nda L. B. Smith and Ayensu 16000. FIGURE 10. Burbacenid paranuensis Hatschbach 29212. (a-f) stages of seedling development, (g) diagram of a (a-g) stages of seedling development, (h) diagram of a seed, (h) transverse section of the seed coat. seed, (i) transverse section of the seed coat.

146 Ayensu some species retain the chlorophyll when dry, others one. As outlined earlier, most Velloziaceae grow in lose it so that the leaves are usually yellow when rather arid environments (Gaff 1971; Owoseye and first dehydrated, then green-up later. In general, Sanford 1972). However, there are a few species species in the same family behave in the same man- adapted to more humid environments. In southern ner. All the Xeropbyta species that I examined lose Africa, for example, Tdbotia elegans grows success- the chlorophyll, except Xerophyta elegans which re- fully at the edge of wet forests. tains it . . . there is a suggestion that X. elegafzs A somewhat different example of an ecological be transferred to a distinct genus, Talbotia, of its shift that occurs in Brazil is demonstrated by the own; perhaps the difference in chlorophyll reaction presence of Barbaceniu gaveensis which grows at an to water stress gives some support to this." outpost on the crest of Pedra da Gavea in Rio de Ecological Shift: Of special interest is the shift of Janeiro. This planalto-type vegetation lies in the plants from a xeric environment to a mesophytic heart of a coastal rain forest. Barbacenia gaveensis

TABLE 3. Nzcmbers of mzcsezcm specimens of Old World Velloziaceae collected in flower in each month of the yertr." Taxon Months in flower Distributionb

Talbotia elegans Balfour 1 1 1 3 4 1 1 Xerophyta aczcmiizata (Baker) N. Menezes 1 1 1 X. drabica (Baker) N. Menezes 1 1 1 X. argeiztea (H. Wild) L. B. Smith & Ayensu 2 1 X, capillaris Baker 1 1 X. clavata Baker 1 1 1 1 X. dasylirioides Baker 1 2 2 3 1 1 2 2 2 1 X, demeesnzaekeriaiza Duvign. & Dewit 1 X. eglandulosa H. Perr. 1 4 1 2 X. equisetoides Bzker 2 2 8 8 5 1 1 X. eylalrii (Greves) N. Menezes 1 X. goetzei (Harms) L. B. Smith & Ayensu 1 X. hzcmilis (Baker) Th. Dur. & Schinz. 2 4 1 4 4 4 2 X. kirkii (Hemsl.) L. B. Smith & Ayensu 2 1 X. nzctans L. B. Smith & Ayensu 1 X. occideetalis L. B. Smith & Ayensu 1 X. pauciramosa L. B. Smith & Ayensu 2 112 5 X. pieifolia Lam. 1 1 1 1 X. retinervis Baker 5 2 1 1 X. rosea (Baker) N. Menezes 1 3 1 1 X. scabrida (Pax) Th. Dur. & Schinz. 2 1 1 2 2 1 X. schlechteri (Baker) N. Menezes 2 1 2 1 X, schnizleinia (Hochst.) Baker 3 2 3 1 1 3 1 1 4 4 1 X. simulans L. B. Smith & Ayensu 1 1 2 1 1 1 3 X. spekei Baker 1 1 6 2 2 2 1 2 4 4 1 X. splendens (Rendle) N. Menezes 1 1 X. squarrosa Baker 2 2 2 1 X. szcaveolens (Greves) N. Menezes 10 10 5 1 1 1 X. trichophylla (Baker) N. Menezes 5 1 X. villosa Th. Dur. & Schinz. 1 2 1 1 X. vicosa Baker I 1 5 3 1 X. weiztzeliana (Harms) Solch 1 X. zambiana L. B. Smith & Ayensu 1 4 2 Xerophyta spp. 2 1 3 3 6 5 1 1 1 1 1,3,4,5,6,8,9 10,11,12,14 a Full data on these specimens may be obtained from the author. Key: 1 South Africa; 2 Lesotho; 3 Swaziland; 4 South West Africa; 5 Botswana: 6 Rhodesia; 7 Mozambique; 8 Zambia; 9 Malawi; 10 Angola; 11 Tanzania: 12 Zaire; 13 Uganda; 14 Kenya; 15 Somali; 16 Ethiopia; 17 Eritrea: 18 Sudan; 19 Nigeria: 20 Arabia; 21 Mada- gascar.

Biology and Morphology of Velloziaceae 147 and other plants that grow in the area are therefore discovered on this continent alone." subjected to constant high relative humidity, an en- Bally stated further that ". . . the potentialities vironmental condition which would not favor many of indigenous plants for our own needs are far from of the typically xeric species of Velloziaceae. It adequately known, be it their medicinal, industrial would be interesting to observe the chlorophyll-hold- (fibres, essential oils, resins, gums, etc.) , agricultural ing capacity of B. gmeeesis under desiccation- (soil-binding, nitrogen-farming, etc.), or horticul- tolerant tests; it might be similar to that of the tural (ornamental plants, succulents) value." African species Talbotiu elegans. In this latter context it is noteworthy that the Future Survival of the Velloziaceae: The large-- gummy substance that exudes from the stems and scale destruction of natural areas in many parts of leafbases of some Ve2loziu species is used to dress the world is proceeding at an unprecedented rate. skin sores in Brazil. A pharmaceutical company is Biologists, and some political authorities, have ex- currently studying the chemistry of this material. A ~ressidtheir concern bver the indiscriminate clear- species of African Xerophytu is alleged to contain ing of evergreen forests in the wake of intensive an active agent that may have a potential in the timber exploitation and the continuous quest for anti-cancer program. These examples support the more agricultural farm lands to satisfy the food and special need for protecting plant species about which fiber needs of man. Similar concern has been ex- we know the least. pressed over the destruction of natural savanna or One of the most beautiful sights in Minas Gerais cerrado vegetation in many tropical areas of the is the flowering of large numbers of Velloziaceae. world. The preservation of these natural areas is in- Yet horticulturists have difficulty in keeping these extricably interlocked with the survival of plants interesting plants alive after transplantation. Al- such as Velloziaceae. though the seeds germinate easily, the crucial prob- In 1966 several members of the "Association lem is how to keep the seedlings alive to maturity. pour l'etude Taxonomique de la Flore c'Afrique The ornamental possibilities of this family have not Tropicale" (A.E.T.F.A.T.) held a symposium in Up- been fully appreciated. To bring the kind of floral psala on the "Conservation of Vegetation in Africa display seen in figure 3 closer to man will require South of the Sahara" (Hedberg and Hedberg 1968). continuous research in horticulture. Reports were presented on the state of the vegeta- tion on the continent and on associated islands, to- ACKNOWLEDGEMENTS gether with several protective measures in operation or proposed for virtually all the countries. It is en- I am most grateful to Drs. Sherwin Carlquist and Thomas R. Soderstrom for offering very useful suggestions. I also couraging to note that the rapid destruction of the thank Drs. W. Don Duckworth and Paul H. Hurd, Jr., natural floras has been of such immense concern to for helping with the identification of the bees which were biologists. For example, in writing about the beautifully illustrated by Mrs. E. H. Froeschner. Ms. Diane Mutomo Hill Plant Sanctuary in Kenya where Xero- Robertson prepared figures 7-10 and Ms. Alice Tangerine figure 4. The following herbaria were kind enough to phyta occurs, P. R. 0.Bally (1968) stated "the con- lend material which was used in recording the flowering servation of the indigenous vegetation is in every months of the species: East African Herbarium, Nairobi; way as important as that of live animals: not only Museum National dPHistoire Naturelle, Paris; The Her- does it give each region its own specific character, barium, Royal Botanic Gardens, Kew; and the British Mu- but the existence of many smaller mammals, birds seum of Natural History, London. Drs. Gert Hatschbach and D. F. Gaff kindly sent me flowers and seeds of the and insects depends very largely on local plant spe- Velloziaceae for the Scanning Electron Microscope studies. cies. . . . The loss in knowledge which we are My thanks are also extended to Dr. Dieter Wasshausen and apt to incur with the destruction of the indigenous the SEM staff of the National Museum of Natural History vegetation cover anywhere in Africa is the more in- for help with the production of the SEM pictures. Ms. calculable as it is bound to involve the disappearance Cynthia Bailey, Research Assistant, was mast helpful in the assembling of data on flowering and for her continuous of plants yet unknown to science: statistics show assistance. Finally, I must thank Dr. Lyman B. Smith for that every year several hundred new species are still sustaining my interest in this family.

LITERATURE CITED ARDITTI, J., B. FLICK, AND D. JEFFREY. 1971. Post-pollination phenomena in orchid flowers 11. Induction of symp- toms by abscisic acid and its interactions with auxin, gibberellic acid and kinetin. New Phytol. 70: 333-341. , AND R. L. KNAUFT. 1969. The effect of auxin, actinomycin D, ethionine, and puromycin on post-pollina- tion behavior by Cymbidium (Orchidaceae) flowers. Amer. J. Bot. 56(6) : 620-628.

148 Ayensu AYENSU, E. S. 1967. Aerosol OT solution-an effective softener of herbarium specimens for anatomical study. Stain Technol. 42: 155-156. . 1968. The anatomy of Barbaceniopsis, a new genus recently described in the Velloziaceae. Amer. J. Bot. 55: 399-405. . 1969a. Leaf-anatomy and systematics of Old World Velloziaceae. Kew Bulletin 23 (2) : 315-335. . 1969b. The identity of Vellozia uaipanensis: Anatomical evidence. Mem. N.Y. Bot. Gard. 18 (2) : 291-298. . 1972. Studies on pollen morphology in the Velloziaceae. Proc. Biol. Soc. Wash. 85(40) : 469-480. . 1973. Phytogeography and evolution of the Velloziaceae. In B. J. Meggers, E. S. Ayensu and W. D. Duck- worth (Eds.). Tropical Forest Ecosystems in Africa and South America: A Comparative Review. Smithsonian Institution Press. . 1974. Leaf-anatomy and systematics of New World Velloziaceae. Smithsonian Contrib. Bot. No. 15: 1-125. BAKER, J. G. 1875. Synopsis of the African species of Xerophyta. Journ. Bot. 13: 231-236. BALLY,P. R. 0. 1968. The Mutomo Hill plant sanctuary in Kenya, pp. 164-166. In Conservation of Vegetation in Africa South of the Sahara. Acta Phytogeographica Suecica 54. Uppsala. BOYD, L. 1932. Monocotyledon seedlings. Trans. Bot. Soc. Edinburgh 31: 1-224. DIJKMAN, M. J., AND S. P. BURG. 1970. Auxin-inducrd spoiling of Vanda blossoms. Amer. Orchid Sw. Bull. 39 (9) : 799-804. DIOGO, J. C. 1926. As fothas das vellozias e seu apparelho regulador da transpira cao. Arch. Mus. Nac. Rio de Janeiro 28: 19-41. DURAND,T., AND H. SCHINZ. 1895. Conspectus Florea Africae. Xe~ophyta5: 270-272. DUTT, B. S. M. 1970. Velloziaceae. Ilz Symposium on Comparative Embroyology of Angiosperms. Bull. Indian Natl. Sci. Acad. No. 41: 373-374. ERDTMAN,G. 1963. Palynology. Ilz R. D. Preston (Ed.) Adk.~ncesin Botanical Research, I. Academic Press, London and New York. GAFF, D. F. 1971. Desiccation-tolerant flowering plants of southern Africa. Science 174: 1033-1034. HEDBERG,I., AND 0. HEDBERG.(Eds.) 1968. Conservation of Vegetation in Africa South of the Sahara. Acta Phytogeographica Suecica 54. Uppsala. HUTCHINSON,J. 1934. The Families of the Flowering Plants, 11. . KUNTH, C. S. 1822. Bromeliaceae. Ilz Synopsis Plantarum Aequinoctialum Orbis Novi. Val. I Paris. 491 pp. MAGUIRE,B. 1969. Velloziaceae botany of the Guayana Highland. Mem. N.Y. Bot. Gard. 55: 399-405. NOHER DE HALAC, R. I. 1969. Nuevos datos sobre la morfologic floral de Bmbaceniopsis boliuiensis con especial referencia a la sexualidad. Kurtziana 5: 293-296. . 1971. Sobre la naturaleza de 10s "appendices petaloides" en Barbacenia purpurea Velloziaceae. Kurtziana 5: 265-269. OWOSEYE,J. A,, AND W. W. SANFORD. 1972. An ecological study of Vellozia schnitzleilzia, a drought-enduring plant of northern Nigeria. J. Ecol. 60: 807-817. PAX, F. 1887. Velloziaceae, pp. 125-127, In A. Engler and K. Prantt (Eds.). Die natiirlichen Pflanzenfarnilien. Teil 2, Abt. 5. Leipzig. , AND K. HOFFMAN. 1930. Amaryllidaceae. In A. Engler and K. Prantt (Eds.). Die natiirlichen Pflanzenfa- milien. Leipzig. SAZIMA,M. 1972. Observacose sobre polinizafSo em Velloziaceae. Suppl. Cienciae Cultura 24(6) : 335. SEUBERT, 1847. Family Velloziaceae in Mart. F1. Bras. 3 pt. 1: 65. SMITH, L. B. 1962. A synopsis of the American Velloziaceae. Contrib. U.S. Nat. Herb. 35: 251-292. , AND E. S. AYENSU. 1974. Classification of the Old World Velloziaceae. Kew Bulletin 29(1). STENAR, H. 1925. Embryologische studien 11. Die Embrologie der Amaryllideen. Diss. Uppsala.

Biology and Morphology of Velloziaceae 149