Close-up photo of the leafy nodes of a stem. A pair of bumps protrude just below the petiole attachment to the stem. Photo by Scott Zona CC BY-NC 2.0.

What are these bumps on the stems of Salvia paryskii? Nobody knows. They are ± in the position of stipules, but they are not likely stipules. For starters, Salvia doesn’t have stipules. Get out the dissecting kit & fire up the SEM. An ontogenetic study is needed. #stipule #Lamiaceae #Botany 🌾🧪🌱

Photo of the stem with alternate, pinnately compound leaves. A pair of large, flattened prickles occupies the stipular position. Photo by Scott Zona CC BY-NC 2.0.

These prickles have fooled me. They are in a similar position as stipules, but they’re not stipules. There is no homology. They are just prickles. The Rutaceae are exstipulate (lack stipules) but are plenty prickly. This is Zanthoxylum simulans. #stipule #Rutaceae #Botany 🌾🧪🌱

Photo of the shoot of a seagrape, which has alternate, simple, round leaves. The ocrea surrounds the stem above the attachment of the petiole to the stem. Photo by Scott Zona CC BY-NC 2.0.

In Polygonaceae, the ocrea, that cylindrical structure above the node (here in Coccoloba uvifera), is believed to be homologous to a stipule. In other families, ocreas may be modified sheathing leaf bases. Homology is very difficult to determine & requires ontogenetic study. #stipule #Botany 🌾🧪🌱

Photo of a shoot with hairy, alternate, pinnately compound leaves. The lowest pair of leaflets clasp the stem like stipules.

These things at the base of the pinnately compound leaf of Lotus maritimus (#Fabaceae) aren’t stipules. They are the lowermost pair of leaflets that clasps the stem like stipules. They are sometimes called “pseudostipules”—an imprecise term. 📷: Thomas Horvath CCBYNC4 #stipule #Botany 🌾🧪🌱

Close-up photo of a pair of ovate stipules that have frilly, dissected margins.

#Burseraceae are described as both stipulate & exstipulate (without stipules). It’s unusual for a family to have both conditions. Neotropical species are exstipulate, but the stipules on this Asian Canarium odontophyllum are unmissable (📷: nicotiana CCBYNC4), #stipule #Botany 🌾🧪🌱

Photo of a shoot tip with opposite, trifoliolate leaves. Emerging leaves are red and subtended by stipules which hold a pool of liquid. A white, dried crust formed along the margin of the pool. Photo by Scott Zona CC BY-NC 2.0.

In Cunonia macrophylla, the large, interpetiolar stipules have colleters, which are large secretory hairs, on their upper surface. The stipules collect a pool of gooey fluid secreted by the colleters (drying white at the margins of the pool). #stipule #Cononiaceae #Botany 🌾🧪🌱

Photo of a leafy shoot with opposite compound leaves. The stipules are semicircular with serrate margins. Photo by Scott Zona CC BY-NC 2.0.

Opposite, compound leaves with stipules are uncommon. Here’s a family that does it: Cunoniaceae, a family in the Oxalidales most abundant in the S. Hemisphere. The stipules are interpetiolar. This is Pancheria billardierei of New Caledonia. #stipule #Cononiaceae #Botany 🌾🧪🌱

Close-up photo of the nodes of a leafy shoot. The leaves are alternate and bipinnately compound. The stipules are pinnatifid. Photo by Scott Zona CC BY-NC 2.0.

More? You want more stipules? I got you covered, starting with the superb stipules of Delonix regia (#Fabaceae). The leaves are bipinnately compound, and the tiny stipules are also pinnately divided. That’s not too surprising: stipules are a part of the leaf. #stipule #Botany 🌾🧪🌱

Close-up of the node and two opposite leaves. Clusters of small, finger-like hairs are in the position usually occupied by stipules. Photo by Scott Zona CC BY-NC 2.0.

Catharanthus roseus (#Apocynaceae) lacks stipules but has colleters (multicellular, secretory hairs) in their place. These colleters may (or may not) be homologous to stipules. More study is needed. #stipule #Botany 🌾🧪🌱

Close-up of a leafy shoot. The leaves are alternate & pinnately compound. The leaflets have serrate margins. The large, ligulate stipule sits in the axil of the leaf. Photo by Scott Zona CC BY-NC 2.0.

The stipules of Melianthus major are intrapetiolar: The pair of stipules at each leaf is fused across the upper (adaxial) side of the petiole to form one large stipule in an unusual position. Very few plant families have intrapetiolar stipules. #stipule #Francoaceae #Botany 🌾🧪🌱

Close-up photo of the node of a plant. The stem is red, and the stipule between the two leaves is green and awl-shaped. Photo by Scott Zona CC BY-NC 2.0.

The stipules of Rubiaceae, which have opposite (paired) leaves, are fused to become interpetiolar stipules. A single pair of stipules is shared between the two leaves. The awl-shaped stipule on this Ixora coccinea has a twin on the other side of the node. #stipule #Rubiaceae #Botany 🌾🧪🌱

Photo of a young shoot of Smilax. The leaves are not fully expanded, but the stipules—here visible as long tendrils—are fully developed. Photo by Scott Zona CC BY-NC 2.0.

Monocots are usually said not to have stipules, but Smilax is an exception. Moreover, the exceptional stipules of Smilax rotundifolia are modified into tendrils. The coil around anything they touch (thigmotropic). #Smilacaceae #stipule #Botany 🌾🧪🌱

Close-up photo of a hand holding a node of a climber with pinnately compound leaves and green legumes. Each tiny stipule has a dark spot, which is an extra-floral nectary. Photo by Scott Zona CC BY-NC 2.0.

What else can stipules do? The dark spots on the tiny stipules of Vicia sativa are extra-floral nectaries. They attract ants, which defend the plant against herbivores. 🐜 #stipule #Fabaceae #EFN #Botany 🌾🧪🌱

Photo of a leafy shoot with alternate, compound leaves. The stipules at the base of every leaf are paired spines. Photo by Scott Zona CC BY-NC 2.0.

Photo of a leafy shoot with alternate, compound leaves. The stipules are inflated, large, woody and are modified as spines. Photo by Scott Zona CC BY-NC 2.0.

Stipules can be defensive: The stipules of Neltuma odorata (1st photo) are modified into spines, but those of an unidentified Vachellia from western Mexico (2nd photo) go one better: they’re also filled with ants that defend their home when disturbed. 🐜 #Fabaceae #stipule #Botany 🌾🧪🌱

Photo of a leafy branch against the sky. The leaves are alternate and pinnately compound. Large, semicircular, pinkish stipules are at the base of each leaf. Yellow, pea-like flowers are present. Photo by Scott Zona CC BY-NC 2.0.

The stipules of Amicia zygomeris (#Fabaceae) of Mexico are large & take on some color, but they don’t last long. They shrivel & fall rather quickly, leaving behind the remainder of the leaf (petiole & leaflets). #stipule #Botany 🌾🧪🌱

Photo of a leafy branch. The leaves are alternate and bipinnate. Large, triangular stipules are visible at the nodes and circled. Photo by Scott Zona CC BY-NC 2.0.

I got stipules for you all week! Stipules are small (usually), paired (usually) bits of leaf tissue at the junction of the petiole & stem. They are part of the leaf, but not all plants have them. A pair of big, obvious stipules of Lysoloma auritum (#Fabaceae) are circled. #stipule #Botany 🌾🧪🌱

Oups #stipule