Famous for their prominent display in traditional Hawaiian leis, plumeria (Plumeria spp.) blossoms grow to 4 inches wide with a pinwheel petal configuration. Depending on the cultivar, these perennial trees grow into bushy shapes or stretch tall with one trunk supporting numerous limbs for maximum blossom support. Thriving in U.S. Department of Agriculture plant hardiness zones 9 through 11, plumerias use their intricate flowers to produce a strong scent.
With dozens of different plumeria varieties, blossom colors vary along with the scents they produce. While some plumerias produce a sweet scent, others generate a spicy vapor. In fact, these tantalizing flowers often smell like other blossoming tree and shrub species, from citrus trees (Citrus spp.) to gardenias (Gardenia jasminoides). The scent's ultimate purpose is for reproductive success. Lightweight seeds emerge from the eventual fruit for germination elsewhere; wind typically transports the seeds away from the mother plant.
If you look carefully at an individual plumeria blossom, it is not a basic flat flower shape. It has a deep, centralized tube connecting to the stem below. Inside this tube are both the male anther and female stigma reproductive parts. Below these parts is the flower's ovary. A specialized nectary resides with the ovary. This gland secretes the intoxicating scent that wafts out of the flower. Because this concentrated scent is directed out of a narrow tube, the vapor is incredibly strong as it exits the blossom. The flower petals themselves do not contribute to the blossom's scent, but they do offer a visual target for pollinators.
Although plumerias are self-pollinating plants, they use insect activity to help each blossom transfer pollen from the anther to the stigma. Because plumeria blossoms have such thin and tubular shapes housing their reproductive parts, they rely on tiny insects, like thrips, to enter the blossom as they are attracted by the strong scent. Typical pollinators, like honeybees and moths, find it difficult to access the nectar. As the small insects move about searching for nectar within the plumeria flower, thrips jostle the anther and effectively exchange pollen grains between the male and female areas.
Plumerias match their prime blooming period with maximum insect activity -- most insects need warm weather to fly for long time periods. The plumeria scent wafts easily on the warm spring winds to attract numerous pollinators. In fact, plumerias lose most of their leaves in the winter to allow spring blossoms to flourish between April and September. Leaves slowly grow back during the summer, but peak spring pollination time is when the flowers take center stage for optimal reproductive success.
- Photo Credit Goodshoot/Goodshoot/Getty Images