Three shrubby species of Caesalpinia adorn the campus of Palomar College, including the vivid red C. pulcherrima and 2 yellow-flowered species, C. mexicana and C. gilliesii.The latter 2 species are now placed in the genus Erythrostemon. They are naturalized from Mexico and South America. C. gilliesii has long, exerted stamens with red filaments. The seeds of C. mexicana are propelled as the pods dry and twist. I have stood by these plants and heard the flying seeds ping off of nearby signs. If you are closely observing the seed pods during the peak "firing season" it might be wise to wear goggles!

Caesalpinia (Libidibia) ferrea is a hardwood tree native to Brazil and Bolivia. It is commonly known as "pau ferro" or Brazilian ironwood; the name "leopard tree" refers to dark patches on the bark. The tree sheds its bark leaving a distinctive, grey and white leopard pattern across the trunk.

According to Wikipedia, leopard tree wood is often used for making fingerboards and bridges for electric guitars and basses. It has a feel and similar tonal properties to rosewood: "The tonal characteristics are said to be between rosewood and ebony, with a slightly "snappier" sound, being slightly brighter than rosewood but with the same depth and warmth. In fact, the Brazilian guitar company Giannini uses laminated pau ferro in many of their classical guitars." The wood may also be used for flooring, fancy furniture, and handgun grips.

Although it has many indications of use for treating different diseases, the seed pods are mainly used by the Amazon people for the antimicrobial treatment of wounds, usually in alcoholic solution. Wikipedia includes more information and references about this valuable South American tree.

For many years I told my students the tree near old chemistry building at Palomar College was brazilwood (Caesalpinia echinata), the red dyewood native to Brazil. In fact, it was the reason Portuguese sailors came to Brazil to harvest the valuable heartwood for the water soluble dye brazilin. I based my ID of this tree on incorrect labels at several reputable botanical gardens. I finally came to the conclusion that my ID was incorrect after taking samples of the heartwood with an increment borer and getting no red coloration when core was placed in water.

One of the most distinctive traits that separate brazilwood from tara is the seed pod. The flattened pods of brazilwood are oval (oblique) and spiny. They are dehiscent and contain only 2 or 3 seeds. The reddish-tinged, indehiscent pods of tara are smooth and elongate with more than 3 seeds. Compare the pod of brazilwood (left) with pods of tara in the above image.

In order to make the dyes colorfast they must be used with various mordants, such as alum, acetic acid (vinegar) and cream of tartar. The action of mordants is very complex, but essentially they serve to chemically bind the dye molecules with the fabric polymer. Different colors are produced depending on the type of mordant and duration of the dye bath, including bright reds and beautiful shades of blue, from light lavender to a deep blue-black. The demand for dyewoods fell off with the development of synthetic substitutes. Both hematoxylin and hematein are still commonly used for bacteriological and histological stains. Logwood and brazilwood dyes are also popular stains for fine wood finishing.

If you lived in England during the late 15th century, your wardrobe was probably drab by today's standards. Your choice of colors was generally limited to blacks, yellow-browns and grays. Reds and purples did exist, but the supply of fast dyes in these colors was very limited, and most of it was used for royalty and ecclesiastical garments. Then, shortly after the famous voyages of Columbus, the Portuguese and British discovered New World sources of brilliant red dyes from two Central and South American trees. These remarkable botanical discoveries forever changed the wardrobes of Europe and led to the birth of two nations.

There are European records of true red dyes during the Middle Ages, primarily from the heartwood of an Asian tree called sappanwood (Caesalpinia sappan). Sappanwood is native to India, Malaya (Malaysia) and Sri Lanka, and is cultivated throughout the Asian tropics. The wood was imported into Europe since medieval times, but only in limited quantities. The dye was a beautiful red, the color of burning coals (in Old French and English "braise") and was called bresil or brasil by the early Portuguese traders. In 1500, Portuguese ships discovered and claimed the Atlantic side of South America that straddled the equator and the tropic of Capricorn. This massive land was called "Terra de Brasil" and later Brazil, because of the dyewood trees (Caesalpinia echinata) that grew there in abundance. Like the closely related sappanwood, the valuable dye from brazilwood (called brazilin) became a popular coloring agent for cotton, woolen cloth and red ink. As with precious cargoes of gold and jewels, Portuguese ships loaded with brazilwood were favorite targets of marauding buccaneers on the high seas.

The heartwood of brazilwood (pau-brazil) has been used in the making of violin bows for more than two centuries and is known to bowmakers and musicians as pernambuco wood. See: Rymer, R. 2004. "Saving the Music Tree." Smithsonian 35 (1): 52-63.

Nickernuts are the marblelike seeds produced in a spiny pod (2 seeds per pod) on a spiny, sprawling shrub that grows along the shores of many Caribbean islands and throughout tropical beaches of the world. In the Caribbean region there are at least three common species: Gray nickernuts (Caesalpinia bonduc) with gray seeds, yellow nickernuts (probably C. ciliata) with yellowish-brown seeds, and C. major with brown or yellowish-brown seeds. The seeds are smooth and shiny at maturity, but continued handling makes them shinier.

All three species are climbing or sprawling shrubs with stout branches armed with sharp, recurved thorns. The twice-compound leaves are also armed with prickles. Racemes of small yellow flowers are produced in the leaf axils, followed by clusters of spiny, two-seeded pods. In C. major the leaflets are slightly larger and the seeds are yellowish or chocolate brown rather than gray. Both species are common throughout the Caribbean and Florida Keys, although C. bonduc appears to be more widespread throughout the tropical Pacific region. The seeds of C. ciliata are apparently not as buoyant as C. bonduc, so they are not as commonly washed ashore along beaches. The smooth, marblelike seeds of nickernuts have a distinctive attachment scar and faint concentric striations.

Although nickernuts are certainly not an economically important member of the Caesalpinia group, they are one of the most interesting. Along beaches of the British West Indies the spiny shrubs form impenetrable thickets and the ground is often littered with seeds resembling shiny gray bird eggs. The seeds are very buoyant with a hard, impervious seed coat and internal cavities between the cotyledons. After floating for months at sea, the durable seeds are fully capable of sprouting in the soft sand of the upper beach zone. Quite often the seeds are still viable and may be grown in potting soil, after first scoring the woody seed coats with a hacksaw blade and soaking them in water for several days.

Nickernuts from tropical islands of the West Indies often follow the Gulf Stream and North Atlantic Current to beaches of northern Europe. Hebrides islanders off the coast of Scotland wore marblelike nickernut seeds as an amulet to ward off evil spirits. Known in the Hebrides as the white Indian nut, the seeds supposedly had other magical powers including a cure for dysentery when the powdered embryo was taken with boiled milk. The seeds contain bonducin, a white, bitter glycoside that is sometimes referred to as "poor man's quinine." Bonducin has been used as a substitute for quinine in the treatment of intermittent malarial fever. In the Caribbean, nickernuts were ground with roasted senna seeds (probably Cassia occidentalis) to make a medicinal coffee or tea. Numerous naturopathic remedies have been attributed to the soothing tea including colds and stomach disorders.

According to Wikipedia, Guilandina (Caesalpinia) bonduc has a pantropical distribution. It typically grows near the coast, in scrub, on sand dunes and on the upper shore. It also occurs inland, in lowland secondary forest and disturbed areas near villages; this may be the result of the seeds being accidentally dropped after being transported for medical purposes or for use as counters in board games. The seeds are buoyant and retain their viability in both fresh and sea water, enabling them to disperse to new coastal locations. When washed up on the shore, they are sometimes known as sea pearls. Maybe this facinating shrub could be grown at Palomar College!

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