Figure 1
Bactris major in cultivation. a. At Montgomery Botanical Center, Coral Gables Florida; young specimen, accession number 94582*G, source Venezuela, 17 yr from planting. Larry Noblick for scale. b. At Fairchild Tropical Botanic Garden, Coral Gables Florida; mature specimen, source British Guiana, accession number 57819A, 50 yr from planting. Mary Collins and David Lee for scale.
Figure 2
Bactris spp., stem anatomy in early development, all stained in tannic acid and resorcin blue stain. TS in a-f. LS in g, h. B. simplicifrons (a and b), stem overall diameter 6mm. a. Periphery of central cylinder, few outer fibers mature. b. Stem center with limited early development of air-lacunae and cell expansion; fiber bundles narrow with few cells, obscure at low magnification (see figure 4 g for closeup view). c-h. B. gasipaes. Stem periphery, overall diameter 20 cm. c. Fiber caps of vascular bundles with limited wall maturation. d. Stem sub-periphery, fiber caps of vascular bundles thin-walled except near phloem of peripheral bundles; ground tissue cells with some horizontal expansion. e. Stem outer center, fiber caps narrower with some wall thickening near phloem. f. Stem center, fiber caps narrow and immature; ground parenchyma cells expanded to form wide intercellular spaces. g. Stem center in LS, air spaces extensively elongated and conspicuous. h. Stem center at a later stage in LS with cell collapse to form air-lacunae. Scale bars: 500 µm in a, same for b; 500 µm in c, same for d-h. fb - fiber bundle, fc - fiber cap, LT - leaf trace, t - tannin cells, X - air lacunae.
Figure 3
Bactris spp., maturing and mature stems; TS in a-l, n; LS in m and o. In c-m stained in crystal violet; stem periphery to left in c-f, and i, j; lignified fibers black in a and b, brown color natural in e and i. a, b, B. major. Sawn mature stem from figure 1 a, diameter 25 mm, outer vascular bundles with heavily lignified (black) fiber caps, central tissue disrupted. b. Detail of regions referred to in text. c, d. B. constanciae. Maturing stems. c. Sub-periphery, fibers of bundle cap progressively immature towards stem center. d. Center, vascular bundles with narrow cap of mature fibers; fiber bundles wide and abundant, disorganized ground tissue an artifact of sectioning. e-m. B. acanthocarpoides. e-h. Maturing stem. e. Periphery, only outer vascular bundles with mature fibers. f. Sub-periphery, innermost vascular bundles with decreasingly narrow fiber caps. g. Center, fiber caps of vascular bundles well developed but with limited wall thickenings, ground tissue cells near vascular bundles stained because of early wall thickening. h. Center, leaf trace (LT) below, axial bundle (AB) above, contrasting amount and maturity of fiber cap. i-m. More mature stem. i. Periphery with progressive maturation of bundle cap fibers toward stem center. j. Sub-periphery, progressive maturation of fiber caps towards stem center (cf figure 3 f); ground tissue cells thicker-walled in association with vascular bundles. k. Center, with maturing caps to vascular bundles; conspicuous fiber bundles; unstained thin-walled cells of ground tissue showing early collapse. l. TS vascular bundle of stem periphery showing progressive maturation of fibers, mature (mf) near phloem, immature (imf) distant from phloem. m. LS of ground tissue of older stem. n, o. B. jamaicana. n. TS mature stem center, collapsed ground tissue cells forming wide air-lacunae, giving appearance of large single cells. o. LS mature stem, ground tissue between two vascular bundles (ve and vb) including wide longitudinally extended air-lacunae, individually delimited by collapsed cells. Scale bars: 5 mm in a, same for b; 500 µm in c, same for d; e 500 µm, same for f-k, i-o except 200 µm in h, and 250 µm in l. AB - axial bundle, fb - fiber bundle, imf – immature fibers, mf - mature fibers, LT - leaf trace, vb - vascular bundle, ve - vessel element, X - air-lacunae.
Figure 4
Bactris spp. Stem structural and developmental details a, b. B. guineensis stained in safranin and Delafield’s hematoxylin. a. TS center, without air-lacunae but secondary division of ground tissue cells. b. LS center to confirm absence of air-lacunae. c-e. B. hirta stained in safranin and alcian green. c. TS periphery with mature tissues. d. Sub-periphery, transitional to center. e. Mature stem center, ground tissue with enlarged intercellular spaces but no air-lacunae. f-h. Fiber types. f. B. acanthocarpoides. Fiber bundle in stem center (c. 80 visible cells). g. B. simplicifrons. TS fiber bundle (8 visible cells) from stem center, ground tissue with starch grains and visible nuclei (arrowheads). h. B. acanthocarpoides. TS mature fiber sheath cap from peripheral vascular bundle, wider part of fibers show stratified secondary cell wall. i-j. B. setulosa. Immature vascular bundles from periphery with extended thin-walled cells of intervening ground tissue. j. Mature peripheral vascular bundles, intervening ground tissue now thick-walled. k. B. major. Macerated fibers contrasting vascular (vf) and non-vascular (fb). Scale bars: 500 µm in a, same for b, 500 µm in c, same for d, e; 100 µm in f; 50 µm in g; 100 µm in h, 500 µm in i, same for j, 250 µm in k. fb - non-vascular fibers, it - intervening ground tissue; n - nucleus; vf - vascular fibers.
