angled angles botanical-gardens clouds columnless-glasshouse conservatories conservatory conservatory-complex construction controlled- temperature curved curves curving dome domes energy-efficient flower-dome foliage garden gardens glass glasshouse greenhouse heating high-tech horticultural horticulture hothouse indoor-gardens light lighting optimized-conditions overcast palm-trees palms plants shrubbery shrubs Singapore steel structure sustainable-building-technologies transparent trees ventilation visibility warm-growing-environment windows agroforestry bactris-gasipaes center-core centre-core cluster cultivated cylinders cylindrical delicacy dietary-fiber dietary-fibre edible exotic food growing-buds heart-of-palm hollow inner-core labor-intensive-harvesting labour-intensive-harvesting long-lived-plant mineral-rich multiple-stems palm palm-cabbage palmetto palmito peach-palms perennial plate salad-vegetable self-suckering taste tropical tropics ubod vegetable vitamin-rich white yellow abundant appearances castor-beans castor-oil castor-oil-plant castor-seeds clusters common cotyledons Euphorbiaceae fast-growing flower flowers highly-toxic inflorescences invasive large large-leaves leaf leaves medicinal palm-of-Christ palma-Christi poison poisonous ricinus-communis seed-pods seedhead shrub spiky-green-seed-capsule spiny surface surfaces textured textures toxic toxins vegetation wasteland-weed weed widespread