holly wood

Holly Wood Tangential Section

Tangential section of wood of Chinese holly. This is how it looks like when you do a cut that’s perpendicular to the radius of the stem. The vertical lines are vessels transporting water from roots to leaves, while the circles are clustered ray cells that function to transport fluids and nutrients radially and laterally (perpendicular to the long axis) within a woody stem. Contributed by … Continue reading Holly Wood Tangential Section

monocot leaf epidermis

Monocot Leaf Epidermis

Microscope image of the epidermis of a spiderwort leaf with well-organized stomata in high density. Stomata (singular stoma) are like little mouths on the leaf surface, specialized in gas-exchange – CO2 enters a plant through them. The opening and closure of stomata are tightly controlled, because when stomata are open, water is escaping from the plant too. Therefore, each plant needs to find a delicate … Continue reading Monocot Leaf Epidermis

Min Ya Dicot

Dicot Leaf Epidermis

Lower leaf epidermis of the stonecrop plants showing puzzle shaped epidermal cells with scattered stomata. Stomata (singular: stoma) are like little mouths on the leaf surface, specialized in gas-exchange – CO2 enters a plant through them. The pairs of sausage-shaped cells, like the lips of these mouths, are “guard cells”, which guard the opening and closure of the stomata. In many flowering plants, the stomata … Continue reading Dicot Leaf Epidermis

MY SITN Aquilegia flower

The Birth of a Flower

Unlike animals, plants possess the ability to generate new tissues and organs throughout their entire lifespans due to the activity of stem cells located in specific sites termed meristems. During the reproductive phase, floral meristem (lower right dome-shaped structure) give rise to different floral organ primordia (the series of bulges), which will eventually grow into the sepals, petals, stamens, staminodia, and carpels of a beautiful … Continue reading The Birth of a Flower


Diamonds in the Leaf

This cross section of an oleander (Nerium oleander) leaf reveals two beautiful mineral crystals inside. Leaf cells are stained red. Adapted to dry conditions, this leaf possess three epidermal layers to prevent water loss, below which there are tightly packed palisade mesophyll cells that are specialized for harvesting light and loosely packed spongy mesophyll cells allowing efficient gas exchange. These calcium oxalate crystals are deposited by specialized … Continue reading Diamonds in the Leaf



These colorful fractions were obtained upon purifying a synthetic small-molecule through flash column chromatography. Though most of these were impurities (bright colors in organic chemistry is usually not a great sign), it served as a reminder to appreciate the beauty in the mundane and seemingly unimportant. Contributed by Carmen Sivakumaren, a graduate student in the Biological and Biomedical Sciences Program at Harvard Medical School.   Continue reading Spectrum

Pseudomonads II

Pseudomonads II

The adaptation of the opportunistic human pathogen Pseudomonas aeruginosa often produces phenotypic diversity. Here, mutants isolated from a genetic screen show notable differences in phenotype: the production of pigments, size, shape, and texture. The blue-green pigmentation seen in some mutants results from the production of pyocyanin, an excreted toxin that kills other microbes and mammalian cells. Whereas, the brown pigmentation is caused by the exocellular pigment, pyomelanin, which … Continue reading Pseudomonads II