Photosynthetic Capacity and Carbon Contribution of Leaves and Bracts to Developing Floral Buds in Cotton

During ontogeny of Gossypium hirsutum L. floral buds (squares), increases in area and dry mass (DM) of floral bracts and the subtending sympodial leaf followed a sigmoid growth curve with increasing square age. The maximum growth rates of the bract area and bract DM occurred between 15 and 20 d after square first appearance (3 mm in diameter). Net photosynthetic rate (P_N) of the sympodial leaf at first fruiting branch position of main-stem node 10 reached a maximum when the subtended square developed into a white flower. Floral bracts had much lower P_N and higher dark respiration than the subtending leaf. The amount of ¹⁴CO₂ fixation by the bracts of a 20-d-old square was only 22 % of the subtending leaf, but 56 % of ¹⁴C-assimilate in the floral bud was accumulated from the bracts, 27 % from the subtending leaf, and only 17 % from the main-stem leaf at 6 h after ¹⁴C feeding these source s. Hence floral bracts play an important role in the carbon supply of developing cotton squares. This revised version was published online in September 2006 with corrections to the Cover Date.     

Physiological causes of cotton fruit abscission under conditions of high temperature and enhanced ultraviolet-B radiation

An experiment was conducted in sunlit controlled environment growth chambers to determine the physiological mechanisms of fruit abscission of cotton ( Gossypium hirsutum L. cv. NuCOTN 33B) grown in high temperature and enhanced ultraviolet (UV)-B radiation. Six treatments included two levels of optimum (30/22°C) and high (36/28°C) day/night temperatures and three levels of biologically effective UV-B radiation (0, 7, and 14 kJ m⁻² per day). Both the temperature and UV-B treatments were imposed from seedling emergence through 79 days after emergence (DAE). High temperature did not negatively affect either leaf net photosynthetic rates (Pn) or abscission of cotton squares (floral buds with bracts) but significantly decreased boll retention. Plants exposed to 7 kJ UV-B radiation retained 56% less bolls than the 0 kJ UV-B control plants at 79 DAE, despite no significant differences in leaf Pn measured at squaring and flowering. At 53 DAE, leaf Pn of plants grown in high UV-B radiation (14 kJ m⁻² per day) decreased by 11%, whereas total non-structural carbohydrate (TNC) concentrations in the leaves, floral buds, and young bolls decreased by 34, 32, and 20%, respectively, compared with the control plants. The high UV-B radiation significantly increased square abscission. Square abscission was not related to leaf TNC concentration but closely correlated with TNC in floral buds ( r  = −0.68, P  < 0.001). Young boll abscission was highly correlated with TNC concentrations in both the leaves ( r  = −0.40, P  < 0.01) and the bolls ( r  = −0.80, P  < 0.001). Our results indicate that non-structural carbohydrate limitation in reproductive parts was a major factor associated with fruit abscission of cotton grown under high temperature and enhanced UV-B radiation conditions.     

Dwarfism Caused by Floral-Bud Removal in Petunia and its Reversal by Gibberellin

The effect of floral-bud removal at different stages of developmenton the plant height and on the total number of buds of Petuniawas studied. Continuous removal of all the floral buds 2 d beforeanthesis caused a marked decrease in plant height and also increasedthe total number of floral buds formed thereafter. At otherstages of floral bud development, bud removal had a lesser effecton both phenomena. Moreover, the plants did not respond to budremoval at anthesis. GA₃ at 25 ppm applied to plants from which the buds had beenremoved, promoted stem elongation. The most pronounced effectwas on plants from which the buds were removed 2 d before anthesis,but it had no effect on plants from which the buds were removedat anthesis stage. The possible involvement of endogenous growth hormones in theresponse of Petunia plants to floral-bud removal and to applicationof GA₃ is discussed. Bud removal, bud number, dwarfness, GA₃, Petunia, plant height     

Shoot morphogenesis associated with flowering in Populus deltoides (Salicaceae)

Temporal and spatial formation and differentiation of axillary buds in developing shoots of mature eastern cottonwood (Populus deltoides) were investigated. Shoots sequentially initiate early vegetative, floral, and late vegetative buds. Associated with these buds is the formation of three distinct leaf types. In May of the first growing season, the first type begins forming in terminal buds and overwinters as relatively developed foliar structures. These leaves bear early vegetative buds in their axils. The second type forms late in the first growing season in terminal buds. These leaves form floral buds in their axils the second growing season. The floral bud meristems initiate scale leaves in April and begin forming floral meristems in the axils of the bracts in May. The floral meristems subsequently form floral organs by the end of the second growing season. The floral buds overwinter with floral organs, and anthesis occurs in the third growing season. The third type of leaf forms and develops entirely outside the terminal buds in the second growing season. These leaves bear the late vegetative buds in their axils. On the basis of these and other supporting data, we hypothesize a 3-yr flowering cycle as opposed to the traditional 2-yr cycle in eastern cottonwood.     

Photosynthesis and carbohydrate partitioning in sweet cherry: Fruiting effects

The effect of fruiting on carbon fixation and retention in leaves was monitored by measuring net photosynthesis (Pn) and total non-structural carbohydrates (TNC) on a seasonal basis on mature fruiting and non-fruiting sweet cherry trees ( Prunus avium L. cv. Bing). Pn was also measured diurnally during stages II and III of fruit development. Pn rates increased to between 18 and 20 mg CO₂ dm^-2 h^-1 during stage II of fruit development and were maintained until harvest. Diurnally, Pn increased in the morning to 20 mg CO₂ dm^-2 h^-1 and this rate continued until sunset. Leaf carbohydrate levels decreased in both fruiting and non-fruiting trees beginning at the equivalent of stage II of fruit growth. Carbohydrates were lower in leaves and woody portions of current, 1- and 2-year-old shoots of fruiting trees. Although differences were found in levels of non-structural carbohydrates, no differences in Pn were found in fruiting vs non-fruiting plants on either a seasonal or a diurnal basis. Pn rates in swet cherry in the field were primarily affected by ontogeny and environment and not by sink strength.     

Photosynthetic and Respiratory Activity of Fruiting Forms within the Cotton Canopy

The supply of photosynthates by leaves for reproductive development in cotton (Gossypium hirsutum L.) has been extensively studied. However, the contribution of assimilates derived from the fruiting forms themselves is inconclusive. Field experiments were conducted to document the photosynthetic and respiratory activity of cotton leaves, bracts, and capsule walls from anthesis to fruit maturity. Bracts achieved peak photosynthetic rates of 2.1 micromoles per square meter per second compared with 16.5 micromoles per square meter per second for the subtending leaf. However, unlike the subtending leaf, the bracts did not show a dramatic decline in photosynthesis with increased age, nor was their photosynthesis as sensitive as leaves to low light and water-deficit stress. The capsule wall was only a minor site of ¹⁴CO₂ fixation from the ambient atmosphere. Dark respiration by the developing fruit averaged −18.7 micromoles per square meter per second for 6 days after anthesis and declined to −2.7 micromoles per square meter per second after 40 days. Respiratory loss of CO₂ was maximal at −158 micromoles CO₂ per fruit per hour at 20 days anthesis. Diurnal patterns of dark respiration for the fruit were age dependent and closely correlated with stomatal conductance of the capsule wall. Stomata on the capsule wall of young fruit were functional, but lost this capacity with increasing age. Labeled ¹⁴CO₂ injected into the fruit interior was rapidly assimilated by the capsule wall in the light but not in the dark, while fiber and seed together fixed significant amounts of ¹⁴CO₂ in both the light and dark. These data suggest that cotton fruiting forms, although sites of significant respiratory CO₂ loss, do serve a vital role in the recycling of internal CO₂ and therein, function as important sources of assimilate for reproductive development.     

Seasonal dynamics of non-structural carbohydrates in two species of mediterranean sub-shrubs with different leaf phenology

The seasonal dynamics of non-structural carbohydrates in the woody organs of two co-existing mediterranean sub-shrubs were analyzed. The two species show different leaf phenology during summer: Linum suffruticosum, maintains many of its green leaves, while Lepidium subulatum sheds most of its leaves. These different leaf phenologies are related to different strategies with regard to summer stress. The maintenance of leaves in Linum is related to its stress tolerance while Lepidium avoids stress by shedding its leaves. The main objectives were to: (1) determine the differences in the seasonal dynamics of non-structural carbohydrates among the main woody organs of both species; (2) verify if differences in the leaf phenology, and hence in the strategy with regard to summer drought, lead to different seasonal patterns of carbohydrate storage and use between the two species; (3) compare the seasonal dynamics of carbohydrates of the two studied sub-shrubs with those of mediterranean trees and shrubs previously reported in the literature. The concentration of soluble sugars (SS), starch and total non-structural carbohydrates (TNC) were assessed monthly, over 17 months, in the main roots, stems and the transition zone between root and shoot systems of both species. Starch storage capacity and SS, starch and TNC pools were calculated. The seasonal pattern of carbohydrate accumulation was similar among the woody organs analyzed, but it differed with those reported for mediterranean trees and shrubs. The two species showed different pools and seasonal patterns of non-structural carbohydrate concentrations in its woody organ, which corresponded to their different extent of leaf shedding. The stress-avoider Lepidium accumulated starch during spring shoot growth as a carbon store for summer respiration and had low pools of SS, whereas the stress-tolerant Linum increased SS during summer drought to maintain photosynthetic activity during summer and had low starch pools and storage capacity. However, irrespective of their different leaf shedding patterns, both species had a similar relative variation of their TNC concentration, which contrasts with previous results on deciduous and evergreen woody species.     

Effect of CO2 enrichment on non-structural carbohydrates in leaves, stems and ears of spring wheat

Field-grown spring wheat (Triticum aestivum L. cv. Dragon) was exposed to ambient and elevated CO₂ concentrations (1.5 and 2 times ambient) in open-top chambers. Contents of non-structural carbohydrates were analysed enzymatically in leaves, stems and ears six times during the growing season. The impact of elevated CO₂ on wheat carbohydrates was non-significant in most harvests. However, differences in the carbohydrate contents due to elevated CO₂ were found in all plant compartments. Before anthesis, at growth stage (GS) 30 (the stem is 1 cm to the shoot apex), the plants grown in elevated CO₂ contained significantly more water soluble carbohydrates (WSC), fructans, starch and total non-structural carbohydrates (TNC) in the leaves in comparison with the plants grown in ambient CO₂. It is hypothesised that the plants from the treatments with elevated CO₂ were sink-limited at GS30. After anthesis, the leaf WSC and TNC contents of the plants from elevated CO₂ started to decline earlier than those of the plants from ambient CO₂. This may indicate that the leaves of plants grown in the chambers with elevated CO₂ senesced earlier. Elevated CO₂ accelerated grain development: 2 weeks after anthesis, the plants grown in elevated CO₂ contained significantly more starch and significantly less fructans in the ears compared to the plants grown in ambient CO₂. Elevated CO₂ had no effect on ear starch and TNC contents at the final harvest. Increasing the CO₂ concentration from 360 to 520 μmol mol^?1 had a larger effect on wheat non-structural carbohydrates than the further increase from 520 to 680 μmol mol^?1. The results are discussed in relation to the effects of elevated CO₂ on yield and yield components.     

Mannitol metabolism in cultured plant cells

Non-structural storage carbohydrates were measured in 9-day-old barley ( Hordeum vulgare L. cv. Brant) primary leaves. Accumulation rates of starch, sucrose and total non-structural carbohydrates (TNC) were approximately linear when measured between 2- and 12-h of light. Progressively higher TNC accumulation rates were observed at higher irradiance levels (i.e., comparing 250, 550 and 1050 ·mol m⁻² s⁻¹). Synthesis of a low-molecular-weight fructan also was enhanced by high irradiances. Low irradiance treatments decreased leaf sucrose levels and there was a corresponding increase in the lag period preceding starch synthesis in the light. Increased starch accumulation rates were usually observed when sucrose concentrations were high. These and other results suggested that cytosolic sucrose concentrations affected starch metabolism in the chloroplast. However, sucrose accumulation rates increased and starch storage decreased when barley seedlings were transferred from 20 to 10°C during the light period. Lowering the night temperature from 20 to 10°C for a single dark period 8-days after planting increased the TNC content of barley primary leaves at the beginning of day nine. In this experiment, TNC accumulation rates of treated and untreated leaves were similar. Changes in the accumulation rate of TNC were usually observed within 2- to 4-h after barley seedlings were exposed to altered environmental conditions. Monitoring rapid changes in leaf carbohydrate levels is a sensitive method for assessing the effects of environmental treatments on photosynthetic metabolism.     

Floral development of Lavatera trimestris and Malva hispanica reveals the nature of the epicalyx in the Malva generic alliance

The epicalyx is a structure below the calyx that is often integrated in floral display. In Malvales, the epicalyx is interpreted to be formed by bracts derived from inflorescence reduction. In this study, we compare the epicalyx and flower development of Lavatera trimestris and Malva hispanica, which are close relatives but show contrasting morphologies. Both species exhibit cymose branching, stipulate subtending leaves, a short plastochron between the appearance of the alternating epicalyx and calyx, a centrifugally developing androecium and a multicarpellar gynoecium. The predominantly trimerous structure and leafy morphology of the epicalyx suggest its origin from a former subtending leaf with leaf‐like stipules. The bilobed epicalyx in M. hispanica represents a loss of the adaxial epicalyx lobe rather than modified bracts. In Malvoideae, the bracts and bracteoles in the flowering branches can be completely absent and are variable in position and number when present. Individual bracts and bracteoles could correspond to further reductions of former subtending leaves instead of precursors of the epicalyx. Although the centrifugal androecium behaves as a branched‐like structure, it is a dynamic complex floral whorl with extended growth capacity. The umbrella in L. trimestris is a swollen part of the style without a well‐understood role in floral or fruit morphology.     

Shading delays bud break in Brachsyegia spiciformis

Whole tree manipulation experiments were performed in the common southern African tree species, Brachystegia spiciformis to test a novel hypothesis that decreasing Total nonstructural carbohydrates (TNC) in the stem could cause bud break in Brachystegia spiciformis. The experimental treatments included fertilization, canopy defoliation, shading and stem heating to decrease stem carbohydrates. None of the treatments significantly decreased mean stem TNC. Likewise the heating, fertilization and defoliation treatments did not significantly affect the date of bud break. However, shading significantly delayed bud break. This delay in bud break could not be attributed to changes in leaf level photosynthetic traits, stem water content, leaf predawn water potential or delayed leaf fall. These results question widely accepted hypotheses about the mechanisms controlling bud break and suggest a carbohydrate homeostatic mechanism.     

Leaf carbohydrate responses to CO2 enrichment at the top of a tropical forest

The accumulation of non-structural leaf carbohydrates is one of the most consistent plant responses to elevated CO₂. It has been found in both fast-and slow-growing plants and is largely independent of the duration of exposure. Changes in leaf quality are thus to be expected, irrespective of other plant responses to atmospheric CO₂ enrichment. However, there is no experimental evidence from tropical forests, the biome with the largest biomass carbon pool. Here we report in situ mesophyll responses of mature tropical trees to a doubling of CO₂. Individually CO₂-enriched leaves on 25 to 35-m-tall forest trees living at 26–35°C can be assumed to experience little sink limitation, and so, may be expected to exhibit no or very little carbohydrate accumulation. We tested this hypothesis using the leaf cup method on leaves accessible via the canopy crane of the Smithsonian Tropical Research Institute in a semi-deciduous tropical forest in Panamá. We also investigated the influence of the leaf-specific light regime, another possible environmental determinant of leaf carbon gain and mobile leaf carbohydrates. Total non-structural carbohydrates (TNC) reached a new steady state concentration after less than 4 days of exposure to twice ambient CO₂ concentration. Against expectation, all four tree species investigated (Anacardium excelsum, Cecropia longipes, C. peltata, Ficus insipida) accumulated significant amounts of TNC (+41 to +61%) under elevated CO₂. The effect was stronger at the end of the daylight period (except for Ficus), but was still significant in all four species at the end of the dark period. In contrast, neither artificial nor natural shading affected leaf TNC. Taken together, these observations suggest that TNC accumulation reflects a mesophyll-bound tissue response specific to elevated CO₂, presumably unrelated to sink limitations. Thus, leaves of tropical forests seem not to be an exception, and will most likely contain more non-structural carbohydrates in a CO₂-rich world. Received: 28 January 1998 / Accepted: 9 April 1998     

DEVELOPMENTAL STUDIES IN PTYCHOSPERMA (PALMAE). I. THE INFLORESCENCE AND THE FLOWER CLUSTER

This paper describes inflorescence structure, including organogenesis of the panicle and flower clusters and vasculature of flowering branches, for two species of Ptychosperma, a genus of arecoid palms. The inflorescence is an infrafoliar panicle with up to four orders of branches in a spirodistichous arrangement conforming to an irregular one-half phyllotaxy. The primordium of the inflorescence is crescentic and the apex has two tunica layers, a group of central cells, and a rib meristem. The distal flower-bearing parts or rachillae of all branches develop acropetally early in ontogeny and are vertically oriented in the bud. Although these rachillae terminate branches of different sizes and orders, they are similar in size and in number of flower clusters produced. Internodes and lower parts of branches develop later. Bracts of four types are produced: a prophyll and empty peduncular bract, bracts which subtend lateral branches, bracts subtending triads, and floral bracteoles. The prophyll and peduncular bracts are tubular and completely closed around all branches until about three months before the flowers reach anthesis. Bracts subtending lateral branches and those that subtend triads enlarge by small amounts of apical, adaxial, and marginal growth to cover subtended apices during early ontogeny, but are small to absent at maturity. Flower clusters are triads of two lateral staminate and a central pistillate flower. Organogenesis indicates that the triad is a sympodial unit. Flowers develop successively, each floral apex bearing a bracteole that subtends the next flower. The vasculature of the inflorescence may be divided into two systems. Bundles of the main axis extend acropetally into the vertically oriented branches as they are initiated and form a central cylinder of larger bundles in each branch. Flower clusters are supplied by a peripheral system of smaller bundles that develop later in relation to the developing floral organs. Bundles of the peripheral system branch frequently, but branching levels are irregular. The irregular branching of peripheral bundles appears related to the phyllotaxy of the flower clusters and the random right or left position of the first flower of the triad. The level of branching of a bundle may depend on the position of a floral primordium with respect to an existing procambial strand. Three (-4) bundles supply each staminate flower and six (-10) the pistillate flower. The histologically specialized inflorescence has stomata and contains abundant starch. Tannins and raphides, spherical silica bodies, and various forms of sclerenchyma appear in sequence and apparently provide support and protection during the long exposure of the branches.     

Leaf phenology and carbon dynamics in six leguminous trees

I documented photosynthetic rates and seasonal stem total nonstructural carbohydrates (TNC) in six leguminous tree species Burkea africana, Baikiaea plurijuga, Erythrophleum africanum, Guibourtia coleosperma, Julbernardia globiflora and Pterocarpus angolensis exhibiting a range of leaf phenological patterns. My goal was to (i) measure photosynthetic characteristics and levels of stored stem carbohydrates in species with varying patterns of leaf phenology and (ii) determine seasonal patterns of stem carbohydrate storage. Despite significant differences in the timing of bud break and leaf cover between the six species, there were no significant differences in maximum photosynthetic rate, quantum efficiency or light saturation point between species. Similarly, there was no significant difference in seasonal mean stem TNC levels despite significant differences in the timing of bud break and leaf cover both between species and within a single species. However, while the average amount of TNC does not seem to be related to leaf phenology, the patterns of carbohydrate use and storage do seem to be related to leaf phenology.     

Why are flowers sweeter than fruits or buds? Variation in extrafloral nectar secretion throughout the floral ontogeny of a myrmecophile

Extrafloral nectar provision during floral ontogeny in ant‐plants has not been widely studied. Extrafloral nectar secretion differed between leaves associated with buds, flowers, and fruits, and peaked during anthesis when pollinators were present. This ontogenetic variation may result from mixed selective pressures involving strategies for defense and mutualist management.     

Carry-over effects of ozone and water stress on leaf phenological characteristics and bud frost hardiness of <Emphasis Type="Italic">Fagus crenata</Emphasis> seedlings

We examined the carry-over effects of ozone (O₃) and/or water stress on leaf phenological characteristics and bud frost hardiness of Fagus crenata seedlings. Three-year-old seedlings were exposed to charcoal-filtered air or 60 nl l^–1 O₃, 7 h a day, from May to October 1999 in naturally-lit growth chambers. Half of the seedlings in each gas treatment received 250 ml of water at 3-day intervals (well-watered treatment), while the rest received 175 ml of water at the same intervals (water-stressed treatment). All the seedlings were moved from the growth chambers to an experimental field on October 1999, and grown until April 2000 under field conditions. The exposure to O₃ during the growing season induced early leaf fall and reduction in leaf non-structural carbohydrates concentrations in the early autumn, as well as resulting in late bud break and reduction in the number of leaves per bud in the following spring. However, O₃ did not affect bud frost hardiness in the following winter. On the contrary, water stress did not affect leaf phenological characteristics, leaf and bud non-structural carbohydrates concentrations and bud frost hardiness. There were no significant synergistic or antagonistic effects of O₃ and water stress on leaf phenological characteristics, concentrations of leaf and bud non-structural carbohydrates and bud frost hardiness of the seedlings. These results show that the carry-over effects of O₃ can be found on the phenological characteristics and leaf non-structural carbohydrates concentrations, although there are almost no carry-over effects of water stress on phenological characteristics and winter hardiness of the seedlings.     

DEVELOPMENT AND PHYLLOTAXIS OF THE VEGETATIVE AXILLARY BUD OF MICHELIA FUSCATA

Tucker, Shirley C. (Northwestern U., Evanston, III.) Development and phyllotaxis of the vegetative axillary bud of Michelia fuscata . Amer. Jour. Bot. 50(7): 661–668. Illus. 1963.—The vegetative axillary buds of Michelia fuscala are dorsiventrally symmetrical with 2 ranks of alternately produced leaves. The direction of the ontogenetic spiral in each of these buds is related both to the symmetry of the supporting branch and to the position of the bud along the branch. On a radially symmetrical branch, all the axillary buds are alike—all clockwise, for example. But in a dorsiventrally organized branch the symmetry alternates from clockwise in 1 axillary bud to counterclockwise in the next bud along the axis. Leaf initiation and ontogeny of the axillary apical meristem conform with those of the terminal vegetative bud. The axillary bud arises as a shell zone in the second leaf axil from the terminal meristem. During this process the axillary apex develops a zonate appearance. The acropetally developing procambial supply of the axillary bud consists wholly of leaf traces. At the nodal level the bud traces diverge from the same gap as the median bundle trace of the subtending leaf. Only the basal 1–2 axillary buds which form immediately after the flowers elongate each year, while the majority remains dormant with 3 leaves or fewer.     

DEVELOPMENTAL POTENTIAL OF AXILLARY BUDS OF WATER HYACINTH,EICHHORNIA CRASSIPES SOLMS. (PONTEDERIACEAE)

Buds axillary to foliage leaves of water hyacinth can elongate either as vegetative stolons or as renewal shoots produced in association with the terminal inflorescence. Stolons differ from renewal shoots in position within the shoot system, morphology, and function. Renewal shoot buds always expand, whereas stolon buds may or may not. A stolon bud develops in conjunction with the subtending leaf; as that leaf matures, the stolon bud reaches a critical period in development. At this point, the bud either continues to expand, producing a stolon, or it stops growth and matures. Maturation is not irreversible, but the probability of a bud expanding decreases as bud age increases. In the field, buds on plants at the water hyacinth mat edge frequently produce stolons, whereas buds on plants inside the mat rarely do so. Leaf morphology also varies between plants in these two regions of the mat. The particular association of leaf and branch type found in the field, however, can be reversed experimentally, indicating that although leaf and bud development are coordinated, the particular course of each is independent.     

Intrapetiolar inflorescence buds in Salacca (Palmae): development and significance

The inflorescence in all species of Salacca is enclosed in a chamber within the leaf base and is exserted through a slit on the abaxial surface of the leaf base. The inflorescence bud is interpreted ds an axillary meristem that becomes radially displaced by adaxial growth of the leaf primordium. A fine channel is produced from the leaf axil to the base of the inflorescence and persists at maturity. The channel and the bud chamber enlarge as the leaf elongates. They are lined by an epidermal layer. There is no cellular breakdown until the collapse and tearing of tissues of the leaf during inflorescence enlargement late in ontogeny. The vegetative bud is positioned about 130⁰ from the axil of its subtending leaf and lies directly below the abaxial inflorescence slit of the leaf above. Vegetative bud development was not observed, hut there is a suggestion of relatively late initiation. The separation of. Eleiodoxa from Salacca is supported by differences in the development of inflorescence and vegetative buds.     

AXILLARY AND DICHOTOMOUS BRANCHING IN THE PALM CHAMAEDOREA

In both Chamaedorea seifrizii Burret and C. cataractarum Martius each adult foliage leaf subtends one axillary bud. The proximal buds in C. seifrizii are always vegetative, producing branches (= new shoots or suckers); and the distal buds on a shoot are always reproductive, producing inflorescences. The prophyll and first few scale leaves of a vegetative branch lack buds. Transitional leaves subtend vegetative buds and adult leaves subtend reproductive buds. Both types of buds are first initiated in the axil of the second or third leaf primordia from the apex, P2 or P3. Later development of both types of bud tends to be more on the adaxial surface of the subtending leaf base than on the shoot axis. Axillary buds of C. cataractarum are similarly initiated in the axil of P2 or P3 and also have an insertion that is more foliar than cauline. However, all buds develop as inflorescences. Vegetative branches arise irregularly by a division of the apex within an enclosing leaf (= P1). A typical inflorescence bud is initiated in the axil of the enclosing leaf when it is in the position of P2 and when each new branch has initiated its own P1. No scale leaves are produced by either branch and the morphological relationship among branches and the enclosing leaf varies. Often the branches are unequal and the enclosing leaf is fasciated. The vegetative branching in C. cataractarum is considered to be developmentally a true dichotomy and is compared with other examples of dichotomous (= terminal) branching in the Angiospermae.