The rhizome in acaulescent plants is thick and well-developed, usually clearly distinguishable from the aerial parts of the plant. Rhizomes are branched in mature plants to varying degrees. These structures are sympodial, i.e. new growth occurs at the base of last season's growth. Old roots are thick and fleshy, often brown to black. Further toward the root tips, new growth develops on branched rootlets that may appear white to black. The portion of the roots furthest away from the rhizome are the most active; they are also the most fragile and can easily break when disturbed.
Leaves
In many acaulescent plants leaves are basal and clearly pedate but some appear palmate (e.g. Helleborus prupurascens), and in other cases leaves are weakly pedate or palmate, often somewhere in between. Leaves are divided into leaflets which can be further divided into many divisions, from part to nearly all their length. The petiole rises directly from the ground level at the base of the previous season's growth, often but not always after the inflorescence which is produced on a leafless scape-like flower stalk. Foliage is large and substantial with conspicuous veining on the undersides. Plants may be glabrous or pubescent or anything in between. Often hairs are most noticeable along the vein margins. In most cases leaves do not overwinter. Helleborus orientalis and its hybrids often have overwintering leathery leaves which persist for up to one year. In other cases leaves are summer and/or autumn dormant. in Helleborus bocconei and Helleborus liguricus, leaves may break dormancy in late autumn and continue to grow throughout the winter months, particularly in mild winter climates. In some species (e.g. Helleborus thibetanus) leaves may completely disappear by mid summer.
Flowers
In acaulescent plants the inflorescence arises directly from ground level at the base of the last season's growth on the rhizome, often but not always before the appearance of true leaves. The flower stalk bears no true leaves but leaf-like bracts are common; consequently, inflorescences may have a bushy appearance. The flower structure of hellebores is somewhat different than that of most other garden plants. Petals typically provide flower color and are often protected by a calyx in most garden plants, but in hellebores no calyx in this sense is present, and the only thing resembling petals comes in the form of tubular nectaries at the base of the sepals. These nectaries provide food for pollinators, though many pollinators are likely attracted by ultraviolet reflections by the much larger sepals. Nectaries last but a short time and are shed along with the stamens by the time carpels begin to swell with fertilized ovules.
Sepals provide the flower color and main horticultural attraction in hellebore flowers, but they function differently than do petals and are much more responsive to environmental factors. Most noticeably, the sepals remain on the flower long after fertilization and never really fall off. They simply change colors and eventually dessicate and deteriorate along with the entire inflorescence. The sepals most commonly number five and consist of two outer sepals, two inner sepals, and one that has an edge inside and outside the edges of adjacent sepals. The outer two sepals provide some protection from the elements and are often a different color than the innermost sepals, particularly after prolonged exposure to sunlight, cold, wind, and various forms of precipitation.
Sepals also undergo a significant amount of photosynthetic activity compared to petals. After fertilization, photosynthetic activity usually increases in hellebore plants so that in the fruiting stage the sepals turn greener or darker green. Citokinins and gibberellins activate chloroplasts after fertilization and the activity is later slowed in the fruiting phase. Throughout this photosynthetic process the peduncles and petioles elongate and sepals broaden and spread apart, which is believed to aid in the distribution of seed. In some plants the sepals do not turn green after fertilization, and this is most obvious in dark flowers that possess permanent anthocyanins.
The interior of the perianth consists of a cluster of stamens tightly surrounding the carpels, which in turn surrounds the pistils. Generally, the pistils are receptive to pollen before the stamens mature, which is useful for cross-pollination and is a fortunate aspect of hellebore morphology from a breeding/hybridizing perspective. As the stamens elongate the anthers begin to produce pollen. The anthers then often curve outward away from the gynoecium. Flowers are hermaphroditic and generally self-fertile, and thus do not need other plants nearby to reproduce.
Comments on individual photos:
1. Notice that the two greenish sepals are the two outermost ones. Also the one that has one outer edge also shows this greening. The two interior sepals are mostly unspoiled. This characteristic is most noticeable on the first flowers of the year. Those that open in more favorable weather a bit later on often remain unaffected or only slightly so. 2. Notice that there is no real calyx here and that the sepals connect directly to the end of the pedicel. Since many hellebore flowers nod, the color on the outside of the sepals can be important for horticultural interest. 3. Example showing photosynthesis in older sepals. The white one on the left opened later. 4. In most hellebore flowers the sepals turn greenish or greener after fertilization regardless of the original color. In some however the color is preserved. Here the anthocyanins remain active and give the perianth a dark appearance even in the fruiting stage. The capsule are also dark which provides an interesting effect. 5. The interior of this flower shows signs of doubling at the nectary level. The necaries are no longer functioning and here this region has taken on the appearance and color of small sepals. 6. The most common double form where the interior develops rows of sepal-like material but the outer sepals are 'normal'. 7. Here the stamens are still tightly wound around the gynoecium, and the anthers have yet to produce mature pollen. At this stage the pistils are almost certainly receptive to pollen and probably have been for some time. 8. Here stamens are beginning to elongate and slowly turn away from the gynoecium. Anthers will soon be producing copious amounts of pollen.
